Free NEET Physics multiple-choice questions on P-N Junction & Rectifiers. Attempt each question and reveal the answer with a full explanation.
A transistor is operated in common emitter configuration at constant V CE = 2V such that a change in the base current from 100 A to 300 A produces a change in the collector current from 10 mA to 20 mA . The current gain ( ) is: 50 75 100 25 In a transistor amplifier, if the phase of the input signal is 0 , the phase of the output signal in a common emitter configuration is: 180 0 90 270 In a half-wave rectifier, if the input peak voltage is V m , the average (DC) output voltage is: V m / 2V m / V m / 2 V m / 2 The current gain of a common-base transistor is 0.98 . If the emitter current changes by 5 mA , the change in base current is: 0.10 mA 4.9 mA 5.0 mA 0.50 mA In a full-wave rectifier using two diodes, the peak inverse voltage (PIV) for each diode is (where V m is peak secondary voltage): 2V m V m V m / 2 2 V m The current gain of a transistor is 80 . If the base current changes by 250 A , what is the change in emitter current? 20.25 mA 20.00 mA 18.75 mA 25.00 mA The max efficiency of a half-wave rectifier is approximately: 40.6 % 81.2 % 50 % 100 % If the base current of a transistor is 50 αA and the emitter current is 5.0 mA , then the current gain β is: 99 100 101 50 The ripple factor of a half-wave rectifier is: 1.21 0.48 0.812 1.11 In a common emitter amplifier, the input resistance R i is 1 k and the load resistance R L is 10 k . If the current gain β is 50 , the voltage gain A v is: 500 50 5 1000 For a common emitter amplifier, the voltage gain is A v . If the collector resistance R C and the input resistance R i are both doubled, the new voltage gain will be: A v 2 A v A v / 2 4 A v In a transistor amplifier, the power gain is 10 4 and the voltage gain is 200 . The current gain is: 50 20 25 100 In a BJT, the relation between current gains and is given by: = 1 - = 1 - = 1 + = 1 + The given circuit has two ideal diodes connected as shown in the figure below. The current flowing through the resistance R 1 will be: 0.43 A 0.86 A 0.5 A 0.25 A A transistor is used as an amplifier in CE mode with a load resistance of 5 k . The input resistance is 1 k and the voltage gain is 250 . The current gain is: 50 125 25 100 An n-p-n transistor is used in a common-emitter circuit. If the collector-emitter voltage is changed by 0.2 V , the collector current changes by 0.004 mA . The output resistance of the transistor is: 50 k 0.8 k 20 k 5 k The maximum efficiency of a full wave rectifier is 81.2 % . If one of the diodes in the full wave rectifier circuit burns out, the efficiency will become: 40.6% 81.2% 20.3% 0% The current gain of a common-emitter amplifier is = 50 . The input resistance is 1 k and the output resistance is 10 k . The power gain is: 25,000 500 2,500 5,000 A transistor has a current gain = 0.99 . If the transistor is connected in common-emitter configuration, what is the base current for a collector current of 10 mA ? 101 A 10 A 1 mA 100 A In a common base amplifier, the phase difference between the input and output voltage is: 0 90 180 270 A transistor is connected in common-collector configuration. This circuit is primarily used for: Impedance matching High voltage gain High power gain Inverting the input signal phase The form factor of a half-wave rectifier is approximately: 1.57 1.11 0.48 1.21 A transistor has a transconductance g m of 50 mA/V and an internal output resistance r o of 20 k . The intrinsic voltage gain is: 1000 2.5 400 100 In a p-n junction diode, the width of the depletion region is W . If a forward bias is applied, the width W : Decreases Increases Remains constant Initially increases then decreases In a bridge rectifier, if one of the four diodes is disconnected (open circuit), the output will be: A half-wave rectified signal Zero output A full-wave rectified signal with half the voltage Unchanged In a transistor, the 'Emitter Injection Efficiency' is defined as the ratio of: Current carried by majority carriers from emitter to the total emitter current Collector current to the emitter current Base current to the emitter current Hole current to the electron current in the base The RMS value of the AC component (ripple) in the output of a half-wave rectifier is given by (where I dc is the DC current and I rms is the total RMS current): I' = I rms 2 - I dc 2 I' = I rms - I dc I' = I rms 2 + I dc 2 I' = I rms + I dc 2 Which type of filter circuit uses an inductor in series with the load and a capacitor in parallel with the load to reduce ripples effectively? L-section filter Shunt capacitor filter Series inductor filter π -section filter In a common emitter amplifier, the input signal voltage is V i = 10 ( t) . If the voltage gain is 50 , the output voltage V o is: 500 ( t + ) 500 ( t) 50 ( t + ) 5 ( t) A forward biased diode is:- The following figure shows a logic gate circuit with two inputs A and B and the output C. The voltage waveforms of A, B and C are as shown below- AND gate NAND gate NOR gate OR gate In the following circuit, the output Y for all possible inputs A and B is expressed by the truth table array ccc A & B & Y 0 & 0 & 1 0 & 1 & 1 1 & 0 & 1 1 & 1 & 0 array array ccc A & B & Y 0 & 0 & 1 0 & 1 & 0 1 & 0 & 0 1 & 1 & 0 array array ccc A & B & Y 0 & 0 & 0 0 & 1 & 1 1 & 0 & 1 1 & 1 & 1 array array ccc A & B & Y 0 & 0 & 0 0 & 1 & 0 1 & 0 & 0 1 & 1 & 1 array A common emitter amplifier has a voltage gain of 50, an input impedance of 100 and an output impedance of 200 . The power gain of the amplifier is 1000 1250 100 500. In a common emitter (CE) amplifier having a voltage gain G , the transistor used has transconductance 0.03 mho and current gain 25. If the above transistor is replaced with another one with transconductance 0.02 mho and current gain 20, the voltage gain will be 2 3 G 1.5 G 1 3 G 5 4 G The capacitance of a p-n junction diode that varies with the applied reverse bias voltage is exploited in which of the following devices? Varactor diode Zener diode Light Emitting Diode Photodiode A npn transistor is connected in common emitter configuration in a given amplifier. A load resistance of 800 is connected in the collector circuit and the voltage drop across it is 0.8 V. If the current amplification factor is 0.96 and the input resistance of the circuit is 192 , the voltage gain and the power gain of the amplifier will respectively be : 4, 3.84 3.69, 3.84 4, 4 4, 3.69 From the circuit of the following Logic gates, the basic logic gate obtained is : NAND gate AND gate OR gate NOT gate A common emitter amplifier circuit is shown in the figure below. For the transistor used in the circuit the current amplification factor, dc =100 . Other parameters are mentioned in the figure. We find that : V BE =+18.2 , V , ; V BC =-3.45 , V and amplifier is working V BE =+18.5 , V , ; V BC =+2.85 , V and amplifier is not working V BE =+20.7 , V , ; V BC =+3.75 , V and amplifier is not working V BE =+21.5 , V , ; V BC =-2.75 , V and amplifier is working In the circuit shown in the figure, the input voltage V i is 20 V, V BE =0 and V CE =0 . The values of I B , I C and are given by I B = 20 A, I C = 5 mA, = 250 I B = 25 A, I C = 5 mA, = 200 I B = 40 A, I C = 10 mA, = 250 I B = 40 A, I C = 5 mA, = 125 In the combination of the following gates the output Y can be written in terms of inputs A and B as A B +A B A B + A B A B A+B The correct Boolean operation represented by the circuit diagram drawn is : NOR AND OR NAND For the logic circuit shown, the truth table is: array ccc A & B & Y 0 & 0 & 0 0 & 1 & 1 1 & 0 & 1 1 & 1 & 1 array array ccc A & B & Y 0 & 0 & 1 0 & 1 & 1 1 & 0 & 1 1 & 1 & 0 array array ccc A & B & Y 0 & 0 & 1 0 & 1 & 0 1 & 0 & 0 1 & 1 & 0 array array ccc A & B & Y 0 & 0 & 0 0 & 1 & 0 1 & 0 & 0 1 & 1 & 1 array For the given circuit, the input digital signals are applied at the terminals A , B and C . What would be the output at the terminal y ? The truth table for the given logic circuit is array ccc A & B & C 0 & 0 & 1 0 & 1 & 0 1 & 0 & 0 1 & 1 & 1 array array ccc A & B & C 0 & 0 & 1 0 & 1 & 0 1 & 0 & 1 1 & 1 & 0 array array ccc A & B & C 0 & 0 & 0 0 & 1 & 1 1 & 0 & 0 1 & 1 & 1 array array ccc A & B & C 0 & 0 & 0 0 & 1 & 1 1 & 0 & 1 1 & 1 & 0 array The output (Y) of the given logic gate is similar to the output of an/a NAND gate NOR gate OR gate AND gate For a transistor connected in common-collector configuration, the voltage gain is approximately: Unity (1) Equal to Equal to Infinite The output (Y) of the given logic implementation is similar to the output of an/a gate. NOR AND NAND OR In a common emitter (CE) amplifier, having a voltage gain G , the transistor used has transconductance 0.03 mho and current gain 25 . If the transistor is replaced with another one with transconductance 0.02 mho and current gain 20 , the load resistance remaining the same, then what is the ratio of the new voltage gain to the original? 2/3 1/2 5/4 3/2 The input signal given to a CE amplifier having a voltage gain of 150 is V i = 2 (15t + 3 ) . The corresponding output signal will be: 300 (15t + 4 3 ) 300 (15t + 3 ) 75 (15t + 2 3 ) 2 (15t + 4 3 ) A transistor is used in common-emitter configuration. Given V c = 10 V , R L = 800 . The voltage drop across R L is 0.8 V . If = 0.96 , then the base current I B is: 41.6 A 1 mA 10 mA 25 A An n-p-n transistor is connected in common emitter configuration in a given amplifier. A load resistance of 800 Ω is connected in the collector circuit and the voltage drop across it is 0.8 V . If the current amplification factor is 0.96 and the input resistance of the circuit is 192 Ω , the voltage gain and the power gain of the amplifier will respectively be: 4, 3.84 4, 4 3.69, 3.84 4, 3.69 A transistor is used in CE configuration. The collector supply is 8V and the voltage drop across a load resistance of 800 in the collector circuit is 0.5 V . If the current gain is 0.96 , then the base current is: 26 A 50 A 12 A 100 A A transistor is connected in common emitter configuration. The collector supply is 8 V and the voltage drop across a load resistance of 800 in the collector circuit is 0.5 V . If the current gain is 0.96 , the base current is: 26 A 13 A 50 A 20 A A transistor is connected in common emitter configuration. The collector supply is 8 V and the voltage drop across a resistor of 800 in the collector circuit is 0.5 V . If the current gain is 0.99 , the base current is: 6.3 A 12.5 A 25 A 50 A A p-n junction diode has a saturation current I s = 10 A at 300 K . What is the approximate voltage required to get a forward current of 10 mA ? (Take k B T/e = 0.026 V ) 0.18 V 0.26 V 0.6 V 0.026 V The Transformer Utilization Factor (TUF) for a center-tapped full-wave rectifier is approximately: 0.693 0.287 0.812 0.406 In the case of a forward biased p-n junction, which of the following is true? The width of depletion layer decreases and the barrier height decreases. The width of depletion layer increases and the barrier height increases. The width of depletion layer decreases and the barrier height increases. The width of depletion layer increases and the barrier height decreases. The barrier potential of a p-n junction decreases with an increase in temperature at a rate of approximately: 2 mV/ C 10 mV/ C 0.1 mV/ C 5 mV/ C The current I in a diode is given by I = I s(e qV/nkT - 1) . What does the 'ideality factor' n represent? The dominant recombination/generation mechanism The ratio of doping concentrations The thickness of the depletion layer The thermal stability of the semiconductor In a BJT, the parameter f T (transition frequency) represents the frequency at which: The common-emitter current gain drops to unity The power gain becomes zero The collector current reaches its maximum The phase shift between input and output is 180 A transistor has a power gain of 40 dB . If the input power is 1 mW , the output power is: 10 W 40 mW 100 mW 1 W The reverse saturation current of a Silicon diode at 25 C is 10 nA . If the temperature is increased to 55 C , the reverse saturation current will be approximately: 80 nA 30 nA 40 nA 100 nA In a transistor, the 'Base Spreading Resistance' is due to the: Resistance of the bulk base region between the base contact and the active junction Resistance of the emitter-base depletion layer Resistance of the collector-base depletion layer Contact resistance of the emitter lead Three identical p-n junction diodes D 1 , D 2 and D 3 are connected across a battery as shown in the figure. If the width of the depletion regions of D 1 , D 2 and D 3 are W 1 , W 2 and W 3 , respectively, then the correct option is: W 1>W 2>W 3 W 3=W 1>W 2 W 3>W 2>W 1 W 2>W 1=W 3 A p-n junction diode can be used as a: Rectifier Amplifier Oscillator Inverter For a transistor, the current ratio α is defined as: I C / I E I C / I B I B / I E I E / I C When an n-p-n transistor is used as an amplifier in common emitter configuration, then: The electrons move from emitter to base The holes move from emitter to base The electrons move from collector to base The holes move from base to collector A transistor is in the 'cut-off' state when: Both junctions are reverse biased Both junctions are forward biased Emitter-Base is forward biased and Collector-Base is reverse biased Emitter-Base is reverse biased and Collector-Base is forward biased In a p-n junction diode, the thickness of the depletion layer is d and the barrier potential is V 0 . When the diode is forward biased with a voltage V , the effective barrier potential becomes: V 0 - V V 0 + V V V 0 The depletion layer in a p-n junction is caused by: Diffusion of charge carriers Drift of charge carriers Impurities in the crystal Potential difference applied In a half-wave rectifier, the input frequency is 60 Hz . The ripple frequency of the output voltage is: 60 Hz 120 Hz 30 Hz 0 Hz The barrier potential of a silicon diode at room temperature is approximately: 0.7 V 0.3 V 1.1 V 0.1 V For a common base configuration of a transistor, the current gain is 0.98 . The current gain for the common emitter configuration is: 49 50 98 100 In a transistor, the base region is: Thin and lightly doped Thick and lightly doped Thin and heavily doped Thick and heavily doped In the common emitter amplifier, the input signal is applied between: Base and Emitter Collector and Emitter Base and Collector Collector and Ground For a transistor action, which of the following statements is correct? The base, emitter and collector regions should have similar size and doping concentrations. The base region must be very thin and lightly doped. Both emitter junction as well as the collector junction are forward biased. The central block is a p-type semiconductor for an npn-transistor. In a common emitter transistor amplifier, if the current gain = 100 and the collector current I C = 5 mA , what is the base current I B ? 50 A 500 A 5 mA 0.5 A The value of current gain for a transistor is 0.9 . If the emitter current is changed by 4 mA , then the change in collector current is: 3.6 mA 4.4 mA 4 mA 0.4 mA Which of the following is correct regarding the depletion region of a p-n junction under reverse bias? Width increases and potential barrier increases Width decreases and potential barrier increases Width increases and potential barrier decreases Width remains same but potential barrier increases For a transistor, the parameter = 100 . If the base current is 20 A , the emitter current will be: 2.02 mA 2.00 mA 1.98 mA 0.2 mA For a common-base transistor amplifier, the input resistance is low because: The emitter-base junction is forward biased The emitter-base junction is reverse biased The collector-base junction is forward biased The base region is very thin A bridge rectifier uses four diodes. If the frequency of the input AC signal is f , the frequency of the ripple in the output DC is: 2f f f/2 4f In the diagram of a transistor, the three regions are labeled Base, Emitter, and Collector. Which region is typically the largest in physical size? Collector Emitter Base All are equal For an NPN transistor to act as an amplifier in CE configuration, the emitter-base junction must be biased and the collector-base junction must be biased. forward, reverse reverse, forward forward, forward reverse, reverse In a common emitter configuration, a transistor has = 50 . If the collector load resistance is 5 k and the input resistance is 1 k , the voltage gain is: 250 50 100 500 In a p-n junction, the thickness of the depletion layer is of the order of: 10 -6 m 10 -10 m 10 -3 m 10 -12 m The dynamic resistance of a diode is defined as: The ratio of a small change in voltage to the corresponding small change in current The ratio of applied DC voltage to the DC current The resistance of the diode under reverse bias only The internal resistance of the power supply A transistor has an = 0.95 . If the emitter current is 10 mA , the collector current is: 9.5 mA 0.5 mA 10.5 mA 10 mA In a semiconductor diode, the 'knee voltage' (cut-in voltage) for Silicon is approximately: 0.7 V 0.3 V 1.1 V 0.1 V For which of the following devices is the V-I characteristic not a straight line passing through the origin? Transistor Metallic resistor at low temperature Ohmic conductor Copper wire A half-wave rectifier is being used to rectify an alternating voltage of frequency 50 Hz . The number of pulses of current per second in the output is: 50 100 25 0 The depletion region in a p-n junction diode is created by: Diffusion of charge carriers Drift of charge carriers Forward biasing Application of magnetic field The relationship between current gain (common base) and (common emitter) is: = 1 - = 1 - = 1 - = 1 In an n-p-n transistor, if the base is made very thin and lightly doped, it is to ensure that: Most of the majority carriers from emitter reach the collector The base current is maximized Recombination in the base is maximized The transistor can handle high power Which of the following circuits represents the forward bias of a p-n junction diode? P side at 0 V and N side at -2 V P side at -2 V and N side at 2 V P side at 3 V and N side at 5 V P side at 0 V and N side at 5 V In a common emitter transistor amplifier, the phase difference between the input signal voltage and the output signal voltage is: π π/2 0 π/4 In a transistor, the current amplification factor β is 100 . The transistor is connected in common-emitter configuration. The value of collector current for a base current of 40 αA is: 4 mA 40 mA 0.4 mA 2.5 mA For an n-p-n transistor to act as an amplifier in the active region, the bias conditions are: Base-Emitter junction Forward Biased, Collector-Base junction Reverse Biased Base-Emitter junction Reverse Biased, Collector-Base junction Forward Biased Both junctions Forward Biased Both junctions Reverse Biased When a p-n junction is forward biased: The potential barrier is lowered and the depletion layer thickness decreases. The potential barrier is raised and the depletion layer thickness increases. The potential barrier is lowered and the depletion layer thickness increases. The potential barrier is raised and the depletion layer thickness decreases. In a p-n junction diode, the current I in the reverse bias is practically independent of the applied voltage until it reaches the breakdown voltage. This current is called: Saturation current Peak current Knee current Drift current The drift current in a p-n junction is caused by: The electric field in the depletion region The concentration gradient of charge carriers The applied forward voltage The high temperature of the junction The depletion layer of a p-n junction diode contains: Immobile ions Free electrons and holes Neutral atoms only No ions at all What is the output frequency of a bridge rectifier if the input frequency is 50 Hz ? 100 Hz 50 Hz 25 Hz 200 Hz The transconductance g m of a transistor is defined as the ratio of the change in collector current I C to the change in: Base-emitter voltage V BE Collector-emitter voltage V CE Base current I B Emitter current I E The depletion layer in a p-n junction has a thickness of 5 10 -7 m and the potential barrier is 0.5 V . The electric field intensity in the depletion layer is: 10 6 V/m 10 5 V/m 2.5 10 -7 V/m 5 10 6 V/m The ripple factor of a half-wave rectifier is approximately: 1.21 0.48 0.81 1.11 Which region of the transistor is most heavily doped? Emitter Base Collector All are equally doped In a transistor, the relation between the change in emitter current I E , change in base current I B and change in collector current I C is: I E = I B + I C I B = I E + I C I C = I E + I B I E = I B I C An oscillator is nothing but an amplifier with: Positive feedback Negative feedback Large gain No feedback In a bridge rectifier, the maximum efficiency is: 81.2% 40.6% 100% 50% A semiconductor device is connected in series with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops almost to zero. The device may be a: P-N junction Intrinsic semiconductor P-type semiconductor N-type semiconductor The current gain of a transistor is 0.95 . What is the change in collector current if the emitter current changes by 2 mA ? 1.9 mA 2.1 mA 0.05 mA 100 mA In a transistor, the base current is 100 A and the collector current is 2 mA . If the collector current changes by 0.5 mA while keeping the base current constant, the collector-emitter voltage changes by 1 V . The output resistance is: 2 k 10 k 5 k 1 k Zener diode is used for:- Rectification Stabilisation Amplification Producing oscillations in an oscillator A transistor is operated in common emitter configuration at constant collector voltage V c = 1.5 V such that a change in the base current from 100 A to 150 A produces a change in the collector current from 5 mA to 10 mA. The current gain ( ) is:- 67 75 100 50 The symbolic representation of four logic gates are given below : The logic symbols for OR, NOT and NAND gates are respectively : (i), (iii), (iv) (iii), (iv), (ii) (iv), (i), (iii) (iv), (ii), (i) A transistor is operated in common-emitter configuration at V C=2 V such that a change in the base current from 100 A to 200 A produces a change in the collector current from 5 mA to 10 mA . The current gain is : 50 75 100 150 The output ( X ) of the logic circuit shown in figure will be X = A . B X = A.B X = A.B X = A + B To get output 1 for the following circuit, the correct choice for the input is A = 0, B = 1, C = 0 A = 1, B = 0, C = 0 A = 1, B = 1, C = 0 A = 1, B = 0, C = 1 For transistor action, which of the following statements is correct? Base, emitter and collector regions should have same size. Both emitter junction as well as the collector junction are forward biased. The base region must be very thin and lightly doped. Base, emitter and collector regions should have same doping concentrations. Consider the following statements (A) and (B) and identify the correct answer. (A) A zener diode is connected in reverse bias, when used as a voltage regulator. (B) The potential barrier of p - n junction lies between 0.1 V to 0.3 V. (A) and (B) both are incorrect (A) is correct and (B) is incorrect. (A) is incorrect but (B) is correct. (A) and (B) both are correct. In half wave rectification, if the input frequency is 60 Hz, then the output frequency would be 30 Hz 60 Hz 120 Hz Zero A full wave rectifier circuit consists of two p-n junction diodes, a centre-tapped transformer, capacitor and a load resistance. Which of these components remove the ac ripple from the rectified output? A centre-tapped transformer p-n junction diodes Capacitor Load resistance In a Schottky diode, the junction is formed between: A metal and an n-type semiconductor A p-type and an n-type semiconductor Two different metals Two different intrinsic semiconductors Given below are two statements: Statement I: Photovoltaic devices can convert optical radiation into electricity. Statement II: Zener diode is designed to operate under reverse bias in breakdown region. In the light of the above statements, choose the most appropriate answer from the options given below. Both Statement I and Statement II are correct Both Statement I and Statement II are incorrect Statement I is correct but Statement II is incorrect Statement I is incorrect but Statement II is correct For the following logic circuit, the truth table is array ccc A & B & Y 0 & 0 & 1 0 & 1 & 1 1 & 0 & 1 1 & 1 & 0 array array ccc A & B & Y 0 & 0 & 0 0 & 1 & 1 1 & 0 & 1 1 & 1 & 1 array array ccc A & B & Y 0 & 0 & 1 0 & 1 & 0 1 & 0 & 1 1 & 1 & 0 array array ccc A & B & Y 0 & 0 & 0 0 & 1 & 0 1 & 0 & 0 1 & 1 & 1 array A logic circuit provides the output Y as per the following truth table : The expression for the output Y is : A.B + A A. B + A B B A full wave rectifier circuit with diodes (D 1) and (D 2) is shown in the figure. If input supply voltage V in = 220 (100 t) volt, then at t = 15 msec D 1 and D 2 both are reverse biased D 1 is forward biased, D 2 is reverse biased D 1 is reverse biased, D 2 is forward biased. D 1 and D 2 both are forward biased In a p-n junction, the diffusion current is: From p-side to n-side From n-side to p-side Zero in forward bias Equal to drift current in reverse bias In a full-wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be: 100 Hz 50 Hz 25 Hz 70.7 Hz Which of the following is NOT correct for a p-n junction? In the depletion region, there are no mobile charge carriers. The potential barrier is due to the fixed ions on either side of the junction. Reverse bias decreases the barrier height. Forward bias increases the diffusion current. The peak voltage in the output of a half-wave rectifier is 10 V . The DC component of the output voltage is: 3.18 V 6.36 V 10 V 7.07 V In the circuit shown, the potential difference between A and B is 4 V . Assuming the diodes are ideal, the current through the 20 Ω resistor is: 0.1 A 0.2 A 0 A 0.05 A The V-I characteristic of a silicon diode is shown in the figure. Calculate the dynamic resistance of the diode at I D = 15 mA . 10 Ω 20 Ω 1 Ω 5 Ω The ripple factor of a full-wave bridge rectifier is: 0.482 1.21 0.121 0.812 In a common emitter transistor amplifier, the audio signal voltage across the collector resistance of 2 k Ω is 2 V . If the current amplification factor of the transistor is 100 and the base resistance is 1 k Ω , the input signal voltage is: 10 mV 1 mV 0.1 V 1 V The depletion layer in a silicon diode is 1 μm wide and its knee voltage is 0.6 V . Then the magnitude of the electric field in the depletion region is: 6 10 5 V/m 0.6 V/m 6 10 -6 V/m 6 10 6 V/m A transistor is operated in common emitter configuration at constant V CE = 10 V . When V BE is changed by 10 mV , the base current changes by 10 μA and the collector current changes by 1 mA . The current gain ( β ) is: 100 10 1000 50 The ripple factor of a full-wave rectifier is: 0.48 1.21 0.812 0.406 To use a transistor as an amplifier: Emitter-base junction is forward biased and collector-base junction is reverse biased. Both junctions are forward biased. Both junctions are reverse biased. Emitter-base junction is reverse biased and collector-base junction is forward biased. In a p-n junction, which of the following is the correct direction of the diffusion current and the drift current? Diffusion: p to n; Drift: n to p Diffusion: n to p; Drift: p to n Diffusion: p to n; Drift: p to n Diffusion: n to p; Drift: n to p A transistor amplifier has a voltage gain of 100 . If the load resistance is doubled and the input resistance is halved, while keeping the current gain constant, the new voltage gain will be: 400 200 100 50 If the current gain of a transistor is 100 , what is the percentage of emitter current that flows through the base? 1% 99% 0.1% 10% The width of the depletion region in a p-n junction diode: Decreases with light doping Increases with heavy doping Decreases with heavy doping Is independent of doping Which of the following describes the 'Avalanche breakdown' in a p-n junction? It occurs due to high velocity of minority carriers hitting the lattice It occurs due to direct rupture of covalent bonds by strong electric field It occurs only in forward bias It occurs only in lightly doped semiconductors with very thin depletion layers Which region of a transistor is kept under reverse bias during normal amplifier operation in active mode? Collector-Base junction Emitter-Base junction Both junctions Neither junction The ratio of the maximum efficiency of a full-wave rectifier to a half-wave rectifier is: 2 0.5 1 4 A transistor has = 100 . The change in collector current is 1 mA . The corresponding change in emitter current is: 1.01 mA 1 mA 0.99 mA 100 mA The reverse saturation current in a p-n junction diode is primarily due to: Drift of minority carriers Diffusion of majority carriers Drift of majority carriers Diffusion of minority carriers In a p-n junction, which of the following processes occurs when the junction is formed? Diffusion of majority carriers and drift of minority carriers Diffusion of minority carriers only Drift of majority carriers only No movement of charge carriers The Peak Inverse Voltage (PIV) of a diode in a center-tapped full-wave rectifier is 2V m , where V m is the peak input voltage. What is the PIV for a bridge rectifier? V m 2V m V m/2 4V m The transfer characteristic ( V o versus V i ) for a transistor as a switch is shown. In which region does the transistor operate as an 'ON' switch? Saturation region Cut-off region Active region Breakdown region In a p-n junction diode, if the temperature is increased, the reverse saturation current: Increases Decreases Remains constant Becomes zero In the common emitter configuration of a transistor, the output resistance is defined as: ( V CE / I C) at constant I B ( V CE / I B) at constant I C ( V BE / I B) at constant V CE ( V BE / I C) at constant V CE The voltage gain of a common emitter amplifier is 50 . If the input signal is V i = 0.1 (100t) V , the output signal is: V o = 5 (100t + ) V V o = 5 (100t) V V o = 0.1 (100t + ) V V o = 50 (100t) V For a common emitter amplifier, the audio signal voltage across the collector resistance of 2 k is 2 V . If the current amplification factor of the transistor is 100 and the base resistance is 1 k , the power gain of the amplifier is: 20000 10000 5000 40000