Business portfolio. Company Google Term Paper Example | Topics and Well Written Essays - 2250 words

Business portfolio. Company Google - Term Paper Example Google was founded by Larry Page and Sergey Brin whilst studying for their doctorate Stanford University in 1995. However, the company was founded in 1998. The company mainly specializes in Internet-related products and services. These products and services include software, search, online advertising technologies, cloud computing. The company also derives a lot from returns from ads. The company also offers online productivity software including Gmail, as well as a social networking site. The other products offered by the company particularly in the desktop section include web browsing applications, instant messaging, and photo editing. Last but not least, the organization leads the development of the mobile operating system for Android.The mission of Google is mainly to organize the information and make it universally useful and accessible by every person. The company’s initial goal before it diversified to collect all global information and organize it.A good mission and vi sion statement should capture the aspirations of the company and should also indicate where the company wants to go, and along with its core products. In the case of Google, the mission and vision statement does not meet the criteria. This is because it aims to organize information and make it universally available to all people. This kind of mission does not even indicate which kind of information it wanted to organize and how people will access given that not everybody across the world has access to the Internet.

Dream Research Project Essay Example for Free

Dream Research Project Essay What is a dream? Dreams are a symbol and link to the inner core of the human subconscious. Dreams as scientist say are stories our brains create while we are sleeping at night. Every dream is not the same, and their qualities depend, at least in part, on the stage of sleep in which they occur. There are different stages of sleep, REM sleep is the one dreams most appear in. REM stands for rapid eye movement in which brain activity is high and signaled by rapid horizontal movements of the eyes. Like all movies, dreams have story lines. Dreams in light sleep, stages 1 and 2, are like children’s movies short and simple. Dreams can be for as long as 20 minutes, to a few seconds. They can vary from normal and mundane, to surreal and bizarre. Dreams can often times drive creative thought, or provoke a sense of inspiration. Scientists believe everybody dreams, but sometimes we forget. We tend to forget when we naturally pass out of sleep through the traditional cycle. If a person is awoken directly from REM sleep (by an alarm clock), they are much more likely remember the dream from that REM cycle. Psychologists have also concluded that our daily activities while we are awake can have an affect on our dreams. However, scientists are unsure of what degree of an impact this makes on us. In one study a group of people wore red-tinted goggles before they went to sleep and there was another group that did not wear the goggles before they went to sleep. Even though anyone did not know the purpose of the study, when group that wore the goggles before they slept had woken the next morning, they had reported seeing more red images in their dreams than the people without goggles. According to First magazine, the average person has about 1. 460 dreams a year. That is 4 dreams every single day. In average you spend 10 to 30 percent of your sleeping time dreaming. You may think that vision is the only â€Å"dream sense† but it is not the only one. Vision is the prominent one, at least for sighted people. About half of all dreams an average person has have sound in them, but only 1 percent has taste, touch, or smell. However, a third of men and 40 percent of women have experienced smell or taste in a dream at least once in there life. Why do dreams occur? There is no shortage of theories as to why we dream. Some see dreaming as an important process through which all species with complex brains analyze and consolidate information. This is supported by the fact that most mammals dream. Other theories conclude that dreaming is nothing more than random brain activity that has little to no logical relevance. Another theory is that dreams reveal wishes or desires we are not aware of during waking hours. Unrelated to that completely another theory is that the human brain contains an ample overload store of information, memories, and emotions. During sleep, nerve cells fire at random, throwing bits of all of them together in random, wild ways. One of the first theories regarding dreams and dreaming was that Sigmund Freud. According to Sigmund Freud, dreams were heavy in symbolism and often showed the true intent and emotions of a human being. Freud saw dreams as wish fulfillment: disguised ways to satisfy unconscious desires that are too upsetting to face consciously. Dreams might therefore offer clues to unconscious conflicts. Freud For instance, sexual desires might appear in a dream as the rhythmic motions of a horseback ride, or conflicting feelings about a parent might appear as a dream about a fight. Freud called dreams the royal road to the knowledge of the unconscious mind. Freuds analysis of dreams brought about much controversy, especially amongst contemporary psychologists. Psychologists of today believe that dreams do have meaning; however, meaning is based upon the individual, not a set logic or theory as proposed by Freud. A very popular theory today is that dreaming specifically through REM sleep is essential for making memories. Several observations support hypothesis. For one when learning a new skill, REM sleep episodes are more frequent and last longer. When the new skill is mastered, those measures drop back to the normal average. Also during REM sleep, areas in the brain’s memory forming regions appear to â€Å"replay† patterns of nerve firing associated with the new learning.

Building A BJT Amplifier Engineering Essay

Building A BJT Amplifier Engineering Essay Students were required to research and design a BJT Amplifier. This amplifier was to be built in the laboratory and tested to verify specifications. Calculations for resistors and capacitors were done and theoretical values were obtained. The circuit was built using Multisim 7 and then simulated to obtain practical values for resistors and capacitors. This is called DC Analysis. When the circuit met the required specifications, building of the BJT Amplifier could begin. Testing of the BJT Amplifier was done using the Feedback FG601 Function Generator which provided an input and a Tektronix 2205 Oscilloscope which showed the output waveform. Also, the Fluke 177 Multi-meter was used when checking for quiescent voltages and currents. The voltage gain, maximum symmetrical swing and the lower cut-off frequency for the BJT Amplifier was tested. The results obtained during tested were compared with the simulated and theoretical results. Success of the BJT Amplifier can only be achieved when the tested values duplicate that of the given specifications. The report that follows records calculations performed, circuits designed and the results of the tests that was done on the BJT Amplifier. List of Abbreviations Voltage gain BJT Bipolar Junction Transistor Current gain Input Impedance Base current Collector current Current across resistor Current across resistor Current across the original emitter resistor Current across the new emitter resistor Current across the unbypassed resistor Resistor used in the potential divider Collector resistor Resistor used in the potential divider Original emitter resistor New emitter resistor (bypassed) Unbypassed resistor Load resistor Base emitter voltage Voltage across the collector and emitter Input voltage Output voltage Voltage across resistor Voltage across the collector resistor Voltage across resistor Voltage across the original emitter resistor Voltage across the new emitter resistor Voltage across the bypassed resistor Introduction It is known that transistors are widely used in electronic devices. This design project is ideal as it enables students to get practical experience in the designing of electrical devices. The practical and theoretical knowledge needed for this design project challenges students as they have to validate calculated values and explain why each process was done. Since the BJT Amplifier has to be designed theoretically, students will understand the limitations provided by the equipment. They will also grasp an appreciation of the simulated circuit model as it relates to the tests performed on the circuit. The theory from Electronics provided valuable knowledge in designing the BJT amplifier. Support was given from lectures based from Engineering Skills and Applications. The practical knowledge was covered in previous laboratory exercises which were designated to familiarizing students with the various equipments. Also, demonstrations were provided by the technicians on the use of the breadboard which is the core building block of the BJT amplifier. BACKGROUND INFORMATION Transistors are important components used in technological devices around the world. Computers, cell phones, and radios are some of the many devices that require transistors as part of their circuit. The transistor is a three terminal, solid state electronic device. In a three terminal device we can control electric current or voltage between two of the terminals by applying an electric current or voltage to the third terminal. This three terminal character of the transistor is what allows us to make an amplifier for electrical signals, like the one in our radio. (cited) The three terminals are the collector terminal, the base terminal and the emitter terminal. There are three possible configurations of a transistor; the common collector, common base and the common collector. In the common emitter amplifier configuration, the emitter terminal is common to both the input and output circuits. The current gain does not have any effect on the collector current , or the collector-emitter voltage . A quiescent point is the operating point of a device which when applied to a device, causes it to operate in a desired fashion. It also refers to the dc conditions of a circuit without an input signal. The Q-point is sometimes indicated on the output characteristics curves for a transistor amplifier. There are different biasing arrangements associated with transistor configurations. These include; simple bias, self stabilizing bias, and H-type bias. The simple bias circuit consists of a fixed bias resistor and a fixed load resistor. For this bias design, the transistor configuration being used is the common emitter. The dc current gain or beta, is the ratio of the dc collector current to the dc base current. This simple bias circuit is similar to the self bias circuit with one difference: the base resistor is returned to the transistor collector instead of the supply voltage. If the transistor used had a high current gain, then the collector voltage would fall. As is connected to the collector then the base current would be reduced to counter the effect. If the transistor had a low value of beta, then the collector voltage would rise. This in turn provides more base current for the transistor to conduct harder and stabilize the q-point. H-TYPE BIASING is the most widely used biasing scheme in general electronics. For a single stage amplifier this circuit offers the best resilience against changes in temperature and device characteristics. The disadvantage is that a couple of extra resistors are required, but this is outweighed by the advantage of excellent stability. The circuits below: The quiescent points are usually fixed for varying collector currents in H-type biasing. If increases, then this will result in an increase in . This increase in the emitter current will flow through the emitter resistor and from the equation V=IR, the voltage across the resistor will increase. This increase in voltage across the emitter resistor will reduce the effective base-emitter voltage resulting in an increase in the stability of the collector current. Also, this type of biasing introduces a potential divider situation, where resistors R1 and R2 fix the base potential of the transistor. With H-type bias, maximum symmetrical sw ing can be calculated. Design OBJECTIVES Various specifications for the design of the BJT Amplifier were given by the rubric. The specifications given are listed in the following; The Voltage Gain must be 50 The Lower Cut-off Frequency must be below 100Hz The BJT Amplifier must be capable of driving a 100KÃŽÂ © load A 15V supply voltage must be used as the source The output voltage must have maximum symmetrical swing A 2N3904 Transistor must be used CHOOSING CONFIGURATION The following transistor configuration comparison chart shows the different types of configurations; Common Emitter Common Base Common Collector (Sedra Smith, 2007) AMPLIFIER TYPE    COMMON BASE      COMMON EMITTER      COMMON EMITTER (Emitter Resistor)      COMMON COLLECTOR (Emitter Follower)   Ã‚  Ã‚   INPUT/OUTPUT PHASE RELATIONSHIP 0 ° 180 ° 180 ° 0 ° VOLTAGE GAIN HIGH MEDIUM MEDIUM LOW CURRENT GAIN LOW  Ã‚ ¡ MEDIUM MEDIUM  Ã‚ ¢ HIGH POWER GAIN LOW HIGH HIGH MEDIUM INPUT RESISTANCE LOW MEDIUM MEDIUM HIGH OUTPUT RESISTANCE HIGH MEDIUM MEDIUM LOW The common emitter transistor amplifier configuration was chosen and not the common base configuration as the common base configuration produces a voltage gain but generates no current gain between the input and the output signals. (Doug Gingrich, 1999) The following figure shows the general configuration of the common emitter transistor amplifier configuration; Figure 1: General configuration of the common emitter transistor amplifier configuration Methodology DC Analysis The function of the DC Analysis is to allow DC biasing of the design to be verified. The DC biasing does not involve capacitors as DC is not transmitted by capacitors. The DC design is mainly used to establish the Q-points in the circuit. Q-points are the operating points in the circuit for which the transistor will perform at optimum performance. The circuit used for the DC Analysis is shown in the following diagram; Figure 2: Circuit used for DC Analysis Choosing and Before DC Analysis could be done, the various components which will be used in the circuit need to be calculated. These components are; , , , . From the specifications given, the voltage supply has a value of 15V and this is used to power the circuit. Before the values of these components could be calculated, the quiescent currents must be known, as well as the current flowing through the potential divider resistor . The data sheet used is based on the 2N3904 transistor. A range for the collector current is given, within which the transistor will operate with optimum performance. Using the Base Emitter ON Voltage vs Collector Current graph found on the data sheet, a value of was read off. The graph used is shown in the following diagram; Figure 3: Graph used to find a collector current The transistor will be built in an environment where the temperature is approximately 25. Hence the 25 line on the graph was used a reference line. From the data sheet, the Base Emitter ON Voltage was given as 0.65V. Hence, using the 25 line and reading off a voltage of 0.65V, the collector current was found to be 1. The base voltage , of the transistor depends on the current flowing through the potential divider. i.e. the current sets the base of the transistor and hence the value of . Any change in the resistance or gain of the transistor would result in an unwanted change in the base current . Also, the potential divider resistors contribute to the input impedance of the amplifier. This input impedance needs to be much more than the output impedance of the function generator. Hence, this is another reason to keep small. was chosen as Calculating The emitter resistor voltage , must be chosen accordingly as this voltage will affect the stability, maximum symmetrical swing and the gain of the amplifier. This voltage should be chosen such that it is greater than the base emitter voltage of the transistor. As mentioned before, the base emitter voltage as taken from the data sheet is 0.65V. This is to ensure that the emitter resistor voltage will not be significantly affected by small changes in . This condition would increase the stability of the transistor. For maximum symmetrical voltage swing, the emitter resistor voltage should be as small as possible. The base current and the collector current will both flow out of the common emitter terminal. Hence, for to remain constant, the base current must be as small as possible to allow negligible current to flow through the base terminal. Assuming the variation possible across the emitter and collector resistors caused variations in is , is calculated using the following equation; (1) The emitter resistor was calculated using the following equation; (2) Calculating From previous statements, For maximum symmetrical swing, half of the remaining voltage should be dropped across the collector resistor . The maximum symmetrical output voltage is calculated using the following equation; (3) Therefore, the voltage across the collector emitter terminal and the collector resistor is 6.75V. From the data sheet, the maximum device dissipation for the NPN 2N3904 transistor is at 25. Since all the power dissipation occurs at the collector junction for the active region, the following equation must be satisfied; (4) This is the range for which the transistor will operate with optimum performance. The power dissipated in the transistor from equation (4) is; , which is well within the specified range. A value for the component was found using the following equation; (5) Calculating and The current flows through the resistor . The value of is calculated using the following equation; (6) Since the current approaches a junction, it splits into and . flows through the potential divider resistor and flows to the base terminal. As previously stated, the base current, must not affect the base voltage by much. Hence the base current is considered negligible and all the current from is assumed to flow through . Hence, is calculated using the following equation; (7) Since some of the component values calculated was not available in stores, the closest value had to be chosen. The standard value that was chosen for each component is shown in the following table; Resistor Calculated Value/ Standard Value/ 6.75 6.8 1.5 1.5 128.5 130 21.5 24 Table 1: Standard values chosen for resistors Calculation of Input Impedance of transistor From the design specifications listed above, the lower cut off frequency must be below 100Hz. Also, as a value for was found using a graph of Current Gain vs Collector Current from the data sheet, a value for was found. The graph used is shown in the following diagram; For a collector current of 1, a gain of 130 was read off from the graph. But since this gain is above the required voltage gain of 50, certain calculations had to be done to reduce this gain and these calculations will be shown in due course. The following equation is used to calculate the input impedance of the transistor; (8) Calculation of Voltage Gain in the Circuit The following equation was used to calculate the voltage gain of the circuit; (9) Calculation of The required voltage gain of the transistor is 50. Hence, in order to reduce this gain, resistors are usually bypassed with the aid of capacitors. In this particular case, the only resistor that needs to be bypassed is the emitter resistor. Using the AC equivalent circuit, the following equation will be used to calculate the value of the unbypassed resistor; (10) where is the unbypassed emitter resistor is From the specification sheet given, is Calculation of new emitter resistor But Hence, if is split into two resistors and , then is found from the following; (11) As there are no standard 1.4kà °Ã‚ Ã…“ ´ resistor is the stores, was used as 1.5kà °Ã‚ Ã…“ ´. The following table illustrates the standard emitter resistors; Resistor Calculated Value/ Standard Value/ 100 100 1400 1500 Table 2: Standard values chosen for emitter resistors CIRCUIT CALCULATIONS Figure 4: Diagram showing circuit analyzed The following circuit calculations involve the standard component values and is based on the circuit in the above diagram.. These circuit calculations show the theoretical value of the quiescent currents and voltages. Theoretical values occur due to the circuit being under ideal conditions. The voltage gain of this circuit will be calculated as well as the maximum symmetrical output voltage across the transistor. The calculations are as follows; which flows through the collector resistor Using the potential divider rule; The voltage drop across is the same as, as both resistors are in parallel. was found on the data sheet as specified previously as . Under ideal conditions, it is assumed that is negligible when compared with as stated previously. for small changes in where is 130 since negligible current flows into the base terminal AC ANALYSIS The AC Analysis is used to calculate the components which would not have worked under DC biasing. These components are , and . If placed in the DC circuit, the capacitors would act as an open circuit, not allowing any current to flow. Also, the input and output impedance of the circuit was calculated. Circuits Used The following circuit was used in the AC Analysis; Figure 5: Circuit used for AC Analysis The following figure illustrates the AC equivalent of the above circuit; Zout Zin Figure 6: Ac equivalent of circuit shown in figure 5 Calculation of Capacitors The capacitor values can now be calculated using the following equation; (12) where is the reactance of the circuit f is the frequency C is the capacitance The capacitors behavior is defined in terms of reactance. The reactance of a capacitor is the ratio of the voltage to the current. The equation relating the reactance to the capacitance is given in equation (12). is the total input impedance of the capacitor (13) where is the input impedance , as the input is taken from the ground to the output terminals of the function generator. (14) Using equation 12; But from the specification sheet, f must be less than 100Hz. f 100 (15) Calculation of For the input coupling capacitor ; Calculation of For the output coupling capacitor ; Where is and Calculation of For the bypass capacitor ; where (16) But As stores does not have these calculated capacitor values, the following standard capacitors were used; Capacitor Calculated Value/ Standard Value/ 0.175 10 0.234 10 14.985 100 Table 3: Standard values chosen for capacitors CIRCUIT CALCULATIONS The following circuit calculations involve the standard component values and are based on the circuit shown in figure 3. These circuit calculations show the theoretical value of the quiescent currents and voltages. Theoretical values occur due to the circuit being under ideal conditions. The voltage gain of this circuit will be calculated as well as the maximum symmetrical output voltage across the transistor. The calculations are as follows; which flows through the collector resistor Using the potential divider rule; (17) The voltage drop across is the same as, as both resistors are in parallel. was found on the data sheet as specified previously as . (18) (19) Under ideal conditions, it is assumed that is negligible when compared with as stated previously. (20) for small changes in (21) where is 130 (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (32) since negligible current flows into the base terminal Figure 6 was used as a reference point to calculate the voltage gain and input impedance of the circuit. Equation (10) was used to calculate the voltage gain of the circuit; The maximum output voltage swing without clipping is calculated as using the following equation; (33) The following equation is used to calculate the input impedance of the circuit; (34) For simplification in calculation, (35) (36) COMPUTER SIMULATION DC Analysis This design was tested theoretically in the previous section and must now be tested on a computer simulation program. The simulation program used to simulate this circuit is Multisim 7. This software creates the circuit design and simulates the circuit practically and not theoretically. All quiescent voltages and currents were determined as well as the cut-off frequency, voltage gain and maximum symmetrical output voltage. The graph analyzer tool on the Multisim program was used to display these graphs. The following figure illustrates the simulation done for the DC Analysis; Voltage Gain The following circuit was used to observe the voltage gain of the BJT Amplifier; Figure 7: Showing circuit used for DC AnalysisThe voltage gain of the simulated circuit is the ratio of the maximum output voltage to the maximum input voltage. The voltage gain of the circuit is given by the equation; The following figure shows the settings used on the oscilloscope to obtain an input and output waveform; The maximum output and input signals was read off from the graph above using the Interpolator Line. Using the above equation, the voltage gain of the circuit was determined as follows; The following figure illustrates the bode plot obtained from the simulation; This graph was used to find the gain of the circuit using the following equation; From the above equation, the gain, in decibels is related to the above equation. Using the Interpolator Line, the gain, was determined to be 34.34. Hence the voltage gain was calculated as follows; The above calculation indicates that the design circuit would produce a satisfactory gain of approximately 50. Therefore the graph in figure 10 confirms that the design would produce a voltage gain of approximately 50. Cut-off Frequency The following bode plot was used to determine the lower cut-off frequency; The figure above was used to determine the lower-cut off frequency of the circuit. The lower-cut off frequency is the frequency at which the gain of the circuit decreases by 3 decibels. The Interpolator Line was placed at a gain of 30.861decibels, as this is the gain which corresponds to the lower-cut off frequency. The lower-cut off frequency was determined to be approximately . This lower cut-off frequency is much less than 100Hz and thus it meets the required specification. The following bode plot was used to determine the upper cut-off frequency; The figure above was used to determine the upper -cut off frequency of the circuit. The Interpolator Line was placed at a gain of 30.816 decibels, as this is the gain which corresponds to the upper-cut off frequency. The upper-cut off frequency was determined to be approximately . Lab Results The final test done on the designed circuit was done in the year 1 laboratory. The actual resistances and capacitances of the standard components used were measured using the LCR meter. The following table illustrates the measured resistances; Resistor Standard Resistance/ Measured Resistance/ Tolerance/% Lower Tolerance/ Upper Tolerance/ 6.8 6.7638 5 6.46 7.14 1.5 1.503 5 1.425 1.575 100 99.81 5 95 105 130 129.95 5 123.5 136.5 24 23.529 5 22.8 25.2 100 kÃŽÂ © 99.233 5 95 105 TABLE 6: Measured resistances AND THEIR TOLERANCE RANGE The following table illustrates the measured capacitances; Capacitor Standard Value/ Measured Value/ TABLE 8: Showing Measured capacitances used in the laboratory The BJT Amplifier was then built on the solder less breadboard. The DC LQD-421 dual power supply and the function generator were used to supply the input voltages. The following diagram shows the circuit built; As seen above, the capacitors were connected across their respective resistors and the Feedback FG 601 function generator was connected to the input capacitor. Before measuring the quiescent points of the circuit, tests had to be done to ensure that the required gain of 50 was achieved. This was done by connecting a Tektronix 2205 dual trace oscilloscope to the AC bias circuit. The channel 1 lead was connected to the input signal via the input capacitor and the channel 2 lead was connected across the output signal via the load. The settings on the Feedback FG 601 function generator were set to produce a 1kHz sine wave with an amplitude of . The channels on the Tektronix 2205 dual trace oscilloscope were grounded and the signals centered. The DC LQD-421 dual power supply was turned on and set to 15V and the Feedback FG 601 function generator and the Tektronix 2205 dual trace oscilloscope also turned on. The channels were switched to AC and the input and output sine waves appeared on the screen. To obtain a clear waveform on the screen, the following settings were used on the Tektronix 2205 dual trace oscilloscope; The Volts/Div setting was set at The channel 1 setting was set at The channel 2 setting was set at The two waveforms were then used to determine the voltage gain of the BJT Amplifier. Using the following equation; The upper and lower cut-off frequencies were found for the BJT Amplifier. This was done by varying the frequency on the Feedback FG 601 function generator and plotting a graph of Gain vs Frequency. The range used for the Feedback FG 601 function generator was; 10Hz 100Hz for lower cut-off frequency The following table illustrates the frequency and gain for lower cut-off frequency; Frequency/Hz Input/mV Output/V Gain 10 0.01 5 50 20 0.01 5 50 30 0.01 5 50 40 0.01 5 50 50 0.01 5 50 60 0.01 5 50 70 0.01 4.8 48 80 0.01 4.6 46 90 0.01 4.2 42 100 0.01 2.6 26 Table4: showing frequencies used to get varying gain The lower cut-off gain was calculated from the equation; The original setting on the Feedback FG 601 function generator was set so that the maximum symmetrical swing of the BJT Amplifier could be determined using the Tektronix 2205 dual trace oscilloscope. This was done by increasing the frequency of the Feedback FG 601 function generator until clipping of the output waveform was seen. It was noted that the BJT Amplifier did not have maximum symmetrical swing as the negative peak of the waveform started clipping after the positive peak waveform. Hence, the positive swing and negative swing was calculated as shown in the following; Positive swing; Negative swing; The maximum voltage swing was found to be; The original setting on the Feedback FG 601 function generator was set as the effect of removing the bypass capacitor was explored. The equipment was first turned off for safety purposes and the bypass capacitor removed. The equipments was then turned on and the settings on the Tektronix 2205 dual trace oscilloscope configured to obtain a measurable waveform. The gain was then calculated using equation (>>>>). Hence, it can be stated that the gain of the BJT Amplifier decreased considerably when the bypass capacitor was removed. The maximum symmetrical swing for the amplifier was then tested. This was done as follows; The frequency of the Feedback FG 601 function generator was increased until clipping occurred. It was seen that maximum symmetrical swing was not observed as the negative peak of the waveform started clipping before the positive waveform. Hence the swing was calculated for both the positive waveform and the negative waveform. The calculations are as follows; Positive swing; Negative swing; The maximum voltage swing was found to be; The Tektronix 2205 dual trace oscilloscope was disconnected from the circuit and the Fluke 177 Multi-meter was used to measure the quiescent points of the circuit. The probes were placed across the different points and their readings were recorded. The Fluke 177 Multi-meter was set at when measuring currents and at DC voltage when measuring voltages. The DC voltage setting was used as the AC would not yield measurable readings. To measure the quiescent currents, wires were stripped and attached to the leads of the probes. The circuit had to be broken at the quiescent current point being measured. Then the wire attached to the probe was inserted into the solder less breadboard so that the wire was in series with the component removed. The removed component was placed where it was originally to ensure continuity in the circuit. This was repeated at all quiescent points. The following table illustrates the measured currents; The following table illustrates the measured currents; Current Value/ TABLE 5: AC ANALYSIS OF CIRCUIT The following table illustrates the measured voltages; Voltage Value/ 0.676 TABLE 4: AC ANALYSIS Quiescent Values Currents I / mA Voltages V / V Calculated Simulated Measured Current I / mA Voltage V/V Current I / mA Voltage V/V Current I / mA Voltage V/V 0.65 0.663 0.676 DISCUSSION The BJT Amplifier was built using the common emitter configuration. It was H-type biased to increase the stability in the transistor. Also, as is affected with temperature a change, the H-type biasing configuration ensures that changes in is minimal. Also, the resistors used were made from carbon. This means that the resistors are not required to have high temperature stability. Without a biasing arrangement, the BJT amplifier will not turn on because it will not be in the operating region according to the specifications (Boylestad, Nashelsky, 1987). The differences in values for quiescent points obtained can be explained because the calculated and simulated values were found under ideal conditions. The component values used varied from the standard values

Ludwig Van Beethoven 9th Symphony Essay -- Music Beethoven Musician Es

Ludwig Van Beethoven 9th Symphony Symphony number nine in D minor, Op.125, the "Choral" is the outstanding piece accompanied with a vocal chorus. Beethoven began concentrated work on the piece in 1822. It occupied him throughout 1823, and he completed it in February 1824. The first performance took place at the Karntnertor Theater in Vienna on May 7, 1824. The deaf composer stood on stage beating time and turning the pages of his score, but the real conducting was done by Michael Umlauf. The first American performance was given on May 20, 1846 by the New York Philharmonic under George Loder. Its performance can never be an ordinary event, just another concert, it is something special because the feeling you get inside when you hear it for the first time. The work of Friedrich von Schiller to set "An die Freude" should be much of the credit of the ninth symphony, but Beethoven's ability to put into music; it’s an art song, which is lovely poetry put into music.   Ã‚  Ã‚  Ã‚  Ã‚  By 1823, Beethoven was not yet sure whether the finale would be vocal or instrumental. Once the symphony was finished, a performance had to be organized. Beethoven saved the premiere for the city that had been his home for the past thirty-one years. At the end of the premiere, Beethoven was still hunched over toward the orchestra, so he was gently turned around so that he might see the applause he could not hear. "The D" turns out to be the "answer" on which the whole orchestra agrees in the great fortissimo summit of that first crescendo, but the tense anticipation of that note is a personal, marvelous, and utterly characteristic touch"(Orga 155).   Ã‚  Ã‚  Ã‚  Ã‚  The ninth symphony is my favorite symphony just because the music is so heavenly. It seems in the beginning of the piece brings a person from darkness to light. Beethoven, I believe, was ahead of his time. To me, he is the greatest composer of all time. His music is not just sounds of music played together in harmony, but a way of life. The music he created for the world is not just to listen to it, but grabs onto the emotion he was setting up. Beethoven's unordinary style cannot ever be copied by any composer or music artist. Today, when we hear music of any kind, we can only thank a certain person, and that person should be Ludwig van Beethoven.   Ã‚  Ã‚  Ã‚  Ã‚  This is how I heard the music, piece by piece with some help to understand and ... ...ers--over the canopy of stars Muss ein lieber Vater wohnen! A loving Father must live. and these lines are then repeated. The religious section of the ode begins as the chorus intones in an awed manner: Ihr stà ¼rzt nieder, Millionen? Millions, do you fall upon your knees? The music rises hopefully toward God and the heavens as the final lines of verse are sung: Ahnest du den Schà ¶pfer, Welt? Do you sense the Creator, world? Such' ihn à ¼berm Sternenzelt!Seek Him above the canopy of stars! ÃÅ"ber Sternen muss er wohnen. Surely He lives above the stars. The last section, from "Seid umschlungen, Millionen!" is repeated triumphantly in counterpoint. A dramatic hush, the music rises steadily. The quartet then re-enters with the following lines from the beginning of the poem: Daughter of Elysium Deine Zauber binden wieder, Thy magic binds together Was die Mode streng geteilt; What tradition has strongly parted, The chorus underlines "Alle Menschen werden Brà ¼der," "All mankind will be brothers." The same line is repeated ecstatically by the quartet, which soars upward to it’s peak. The orchestra and chorus re-enter at a rapid tempo to bring the movement to its conclusion.

Chemistry Study Guide Acids and Alkalis

Interactive Science 2B Chapter Summary | | Chapter 10 ComMon Acids and Alkalis 10. 1 Acids and Alkalis 1. Acids taste sour. Many fruits contain acids. 2. The three mineral acids commonly found in the laboratory are hydrochloric acid, sulphuric acid and nitric acid. 3. Alkalis taste bitter and feel soapy or slippery. 4. The common alkalis found in the laboratory are sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution and ammonia solution. 0. 2 Acid-Alkali Indicators 1. An acid-alkali indicator shows different colours in acids and alkalis. It can be used to test acids and alkalis. 2. Natural indicators can be made from some deeply coloured plants. 3. Acids turn blue litmus paper red whereas alkalis turn red litmus paper blue. Distilled water does not change the colour of litmus paper. It is a neutral substance. 4. The pH value shows the degree of acidity or alkalinity of a substance. 5. The pH value of a substance can be measured by using universal indic ator, pH paper or a pH meter. 6.Low pH values mean high acidity (or low alkalinity). 7. High pH values mean high alkalinity (or low acidity). 8. Substances with pH values < 7 :acidic; pH values = 7 :neutral; pH values > 7:alkaline. 10. 3 Acids and Corrosion 1. Dilute acids react with some metals and produce hydrogen. 2. Test for hydrogen: Put a burning splint near the mouth of a test tube containing the gas. If the gas is hydrogen, it burns with a ‘pop' sound. 3. The rate of reaction of some metals with dilute hydrochloric acid or dilute sulphuric acid: maznesium > zinc> iron > copper (no reaction) . Carbonates react with acids and give carbon dioxide. 5. Marble and limestone mainly contain calcium carbonate. They are used as building materials and they can be corroded by acids. 10. 4 Safety Related to the Use of Acids and Alkalis 1. Strong acids / alkalis are corrosive. Weak acids / alkalis are generally less corrosive. 2. Dilute acids / alkalis contain a low percentage of ac ids / alkalis. Concentrated acids / alkalis contain a high percentage of acids / alkalis. 3. Concentrated strong acids and alkalis are highly corrosive. 4. Safety measure in handling strong acids and alkalis |Reason | |(a) Stick the hazard warning label ‘corrosive ‘ on the surface|To warn users about the corrosive property of the chemicals. | |of the container. | | |(b) Wear safety spectacles. |To prevent the acids and alkalis from getting into the eyes. | |(c) Put on protective gloves. |To prevent our skin from contact with the acids or alkalis. | |(d) Wear laboratory coat. |To prevent damage of clothing and body. |(e) Work in a fume cupboard. |To prevent vapours of the acids or alkalis from irritating our| | |eyes and respiratory system. | 5. To dilute a concentrated acid or alkali, always add it slowly to a large amount of water with stirring. Never pour water into a concentrated acid or alkali. 6. The first step in treating acid or alkali spillage on our body is to w ash with plenty of water. 10. 5 Acid Rain 1. Clean or normal rain has a pH value of 5. 6. 2. Acid rain has a pH value lower than 5. 6. 3. Practice test:Â  answer keyAcid rain is mainly caused by the acidic pollutant gases sulphur dioxide and nitrogen oxides. 4. The main sources of sulphur dioxide and nitrogen oxides in the air are motor vehicles, power stations and factories. 5. Acid rain may ? corrode structures made of metals, marble and limestone, ? kill fish and plants in lakes and rivers, and ? slow down plant growth and even kill plants. 6. The government, industries and citizens should work together to reduce the release of sulphur dioxide and nitrogen oxides, which cause acid rain. 10. 6 Neutralisation 1. An alkali and an acid can neutralise each other. . Neutralisation occurs when an alkali is mixed with an acid until the resulting solution becomes neutral (pH = 7). 3. When an acid is neutralised with an alkali, a salt and water are formed. The word equation for neutralisation is: Alkali + Acid (Salt + Water 4. Antacids are weak alkalis used to neutralise excess acid in the stomach. 5. Weak acids, such as eth anoic acid in vinegar, can be used to neutralise the alkaline stings of wasps. 6. Weak alkalis, such as baking soda (sodium hydrogencarbonate), can be used to neutralise the acidic stings or bites of bees, ants and mosquitoes. . Weak alkalis, such as slaked lime (calcium hydroxide) and powdered limestone, can be added to acidic soil to raise the pH for plant growth. 8. Acids in industrial wastes can be neutralised by adding alkalis such as sodium hydroxide, while alkalis can be neutralised by adding acids such as sulphuric acid. 10. 7 Daily Uses of Acids and Alkalis 1. Acids and alkalis can be used in cleaners to remove stains and grease. 2. Acids such as ethanoic acid can be used to preserve food. 3. Acids can be used to prevent the browning of fruits. ———————– [pic] [pic]

Bureaucracies - Max Webers Iron Cage essays

Bureaucracies - Max Webers Iron Cage essays Discuss the functions and dysfunctions of bureaucracies that is the characteristics of bureaucracies as well as its derivation and intended goals - support the points with situations in America today Despite Max Webers description of bureaucracies as iron cages, bureaucracies are not necessarily a bad thing. Once upon a time, patronage, nepotism, or bribery secured an individuals advancement in government and in society. Today, in the modern civil service, performing well on an exam and showing merit in school and possessing technical qualifications can now secure an individual a high government position. Bureaucracy is characterized by a hierarchical organization having a strict division of labor into spheres of influence and clear norms and rules about behavior, promotion, salary and disciplinary procedures. The advantage to this can be seen in a corporation, where there are IT departments, human resource departments, and other departments where individuals are segmented according to their unique skills, and given clear duties to make things more efficient-there is no confusion as to what is my job or how should I proceed if I have a complaint? Bureaucracies were a vast imp rovement upon the system of courtly favoritism, where proximity to the ruler determined ones level of power, and also feudalism, where birth rather than merit determined ones place in life. However, the downside is the not my job mentality of a bureaucracy is that it can create laziness and intransigence. Slavish following of the rules can create irrational responses-and that may include the way that people are promoted within the organization, leading to less, rather than more qualified people in charge. For example, it could be argued that many people would make good high school teachers who do not have teaching degrees. But the requirement to become a teacher in many states is a B....