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Q 1. In the middle of the depletion layer of a reverse- biased {tex} p - n {/tex} junction, the
electric field is zero
potential is maximum
electric field is maximum
potential is zero.
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Q 2. In the circuit below, {tex} A {/tex} and {tex} B {/tex} represent two inputs and {tex} C {/tex} represents the output. The circuit represents
OR gate
NOR gate
AND gate
NAND gate
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Q 3. If in a {tex} p - n {/tex} junction diode, a square input signal of {tex} 10 \mathrm { V } {/tex} is applied as shown
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Q 4. In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be
100 {tex} \mathrm { Hz } {/tex}
70.7 {tex} \mathrm { Hz } {/tex}
50 {tex} \mathrm { Hz } {/tex}
25 {tex}\mathrm { Hz } {/tex}
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Q 5. In common base mode of a transistor, the collector current is {tex} 5.488 \mathrm { mA } {/tex} for an emitter current of {tex} 5.60 \mathrm { mA } {/tex}. The value of the base current amplification factor ( {tex} \beta {/tex} ) will be
48
49
50
51
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Q 6. The circuit has two oppositely connect ideal diodes in parallel. What is the current following in the circuit?
{tex} 1.71 \mathrm { A } {/tex}
{tex} 2.00 \mathrm { A } {/tex}
{tex} 2.31 \mathrm { A } {/tex}
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Q 7. A solid which is transparent to visible light and whose conductivity increases with temperature is formed by
metallic binding
ionic binding
covalent binding
van der Waals binding
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Q 8. In the ratio of the concentration of electrons that of holes in a semiconductor is {tex} 7 / 5 {/tex} and the ratio of currents is {tex} 7 / 4 {/tex} then what is the ratio of their drift velocities?
{tex} 4 / 7 {/tex}
{tex} 5 / 8 {/tex}
{tex} 4 / 5 {/tex}
{tex} 5/4 {/tex}
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Q 9. The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than {tex} 2480 \mathrm { nm } {/tex} is incident on it. The band gap in (eV) for the semiconductor is
0.5 {tex} \mathrm { eV } {/tex}
0.7 {tex} \mathrm { eV } {/tex}
1.1 {tex}\mathrm { eV } {/tex}
2.5 {tex} \mathrm { eV } {/tex}
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Q 10. A working transistor with its three legs marked {tex} P , {/tex} {tex} Q {/tex} and {tex} R {/tex} is tested using a multimeter. No conduction is found between {tex} P {/tex} and {tex} Q . {/tex} By connecting the common (negative) terminal of the multimeter to {tex} R {/tex} and the other (positive) terminal to {tex} P {/tex} or {tex} Q {/tex}, some resistance is seen on the multimeter. Which of the following is true for the transistor?
It is an npn transistor with {tex} R {/tex} as collector.
It is an npn transistor with {tex} R {/tex} as base.
It is a pnp transistor with {tex} R {/tex} as collector.
It is a pnp transistor with {tex} R {/tex} as emitter.
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Q 11. In a common base amplifier, the phase difference between the input signal voltage and output voltage is
0
{tex} \pi / 2 {/tex}
{tex} \pi / 4 {/tex}
{tex} \pi {/tex}
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Q 12. In the following, which one of the diodes is reverse biased?
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Q 13. When npn transistor is used as an amplifier
electrons move from base to collector
holes move from emitter to base
electrons move from collector to base
holes move from base to emitter.
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Q 14. In a common base amplifier the phase difference between the input signal voltage and the output voltage is
0
{tex} \pi / 4 {/tex}
{tex} \pi / 2 {/tex}
{tex} \pi {/tex}
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Q 15. For the given combination of gates, if the logic states of inputs {tex} A , B , {/tex} {tex} C {/tex} are as follows {tex} A = B = C = 0 {/tex} and {tex} A = B = 1 , C = 0 {/tex} then the logic states of output {tex} D {/tex} are
{tex} 0,0 {/tex}
{tex} 0,1 {/tex}
{tex} 1,0 {/tex}
{tex} 1,1 {/tex}
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Q 16. While a collector to emitter voltage is constant in a transistor, the collector current changes by {tex} 8.2 \ { mA } {/tex} when the emitter current changes by {tex} 8.3 \ { m } A {/tex}. The value of forward current ratio {tex} h {/tex} is
{tex}82{/tex}
{tex}83{/tex}
{tex}8.2{/tex}
{tex}8.3{/tex}
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Q 17. The output of a {tex}NAND{/tex} gate is 0
If both inputs are 0
If one input is 0 and the other input is 1
If both inputs are 1
Either if both inputs are 1 or if one of the inputs is 1 and the other 0
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Q 18. A semiconductor {tex}X{/tex} is made by doping a germanium crystal with arsenic {tex} (Z = 33){/tex}.
A second semiconductor {tex}Y{/tex} is made by doping germanium with indium {tex} (Z = 49){/tex}.
The two are joined end to end and connected to a battery as shown.
Which of the following statements is correct
{tex} X {/tex}is {tex} P {/tex}-type, {tex} Y {/tex}is {tex} N {/tex}-type and the junction is forward biased
{tex} X {/tex}is {tex} N {/tex}-type, {tex} Y {/tex}is {tex} P {/tex}-type and the junction is forward biased
{tex} X {/tex}is {tex} P {/tex}-type, {tex} Y {/tex}is {tex} N {/tex}-type and the junction is reverse biased
{tex} X {/tex}is {tex} N {/tex}-type, {tex} Y {/tex}is {tex} P {/tex}-type and the junction is reverse biased
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Q 19. In a {tex}PNP{/tex} transistor the base is the {tex} N {/tex}-region. Its width relative to the {tex}P{/tex}-region is
Smaller
Larger
Same
Not related
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Q 20. The combination of gates shown be a process 
{tex}\mathrm {AND}{/tex} gate
{tex}\mathrm{XOR}{/tex} gate
{tex}\mathrm{NOR}{/tex} gate
{tex}\mathrm{NAND}{/tex} gate
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Q 21. A common emitter amplifier is designed with {tex} N P N {/tex} transistor {tex} ( \alpha = {/tex} {tex} 0.99 ) . {/tex} The input impedance is {tex} 1\ { K } \Omega {/tex} and load is {tex} 10\ { K } \Omega {/tex}. The voltage gain will be
{tex}9.9{/tex}
{tex}99{/tex}
{tex}990{/tex}
{tex}9900{/tex}
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Q 22. The relation between {tex} \alpha {/tex} and {tex} \beta {/tex} parameters of current gains for a transistors is given by
{tex} \alpha = \frac { \beta } { 1 - \beta } {/tex}
{tex} \alpha = \frac { \beta } { 1 + \beta } {/tex}
{tex} \alpha = \frac { 1 - \beta } { \beta } {/tex}
{tex} \alpha = \frac { 1 + \beta } { \beta } {/tex}
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Q 23. A gate in which all the inputs must be low to get a high output is called
A {tex}\mathrm{NAND}{/tex} gate
An Invertor{tex} {/tex}
A {tex}\mathrm{NOR}{/tex} gate
An {tex}\mathrm{AND}{/tex} gate
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Q 24. The {tex} i - V {/tex} characteristic of a {tex} P - N {/tex} junction diode is shown below. The approximate dynamic resistance of the {tex}P-N{/tex} junction when a forward bias of {tex}2{/tex} {tex}volt{/tex} is applied 
{tex} 1\ \Omega {/tex}
{tex} 0.25\ \Omega {/tex}
{tex} 0.5\ \Omega {/tex}
{tex} 5\ \Omega {/tex}
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Q 25. On increasing the reverse bias to a large value in a {tex} P N- {/tex}junction diode, current
Increases slowly
Remains fixed
Suddenly increases
Only fixed ions
