1.
An n-type substance is: (D) Is not based on logic algebra
(A) Positively charged (B) Negatively charged 18. In a semi-conducting material the mobilities of
(C) Neutral (D) None of the above electron and hole are μe and μe respectively.
2. Depletion region has:
Which of the following is true?
(A) Electrons only (B) Holes only
(C) Neither electrons nor holes (D) both (A) μe > μh (B) μe = μh (C) μe < μh (D) μe > 0;
electrons and holes μh >0
3. The application of external potential 19. To make a full wave rectifier, the ac input be
difference across a p-n junction is called: applied across:
(A) Rectification (B) Biasing (C) Modulation (D)
Polarization
4. A junction diode when forward biased
offers:
(A) Zero resistance (B) Infinite resistance
(C) low resistance (D) High resistance
5. If the input of frequency 50 Hzis applied to (A) AB (B) BC (C) AD (D) AC
full wave rectifier, the frequency of output 20. A transistor has a base current of 1mAemitter
DC voltage is: current 100 mA. The current gain of resistor is:
(A) 25 Hz (B) 50 Hz (C) 100 Hz (D) 200 (A) 100 mA (B) 1 mA (C) 99 mA (D) none of
Hz these
6. The diode which converts light energy into 21. The change in collector current, in a transistor
electric energy: of AC current gain 150, for 100 μA changein its
(A) photo-diodes (B) Photo voltaic cells base current will be:
(C) Light emitting diode (D) None of them (A) 0.15 A (B) 0.015 A (C) 1.5 A (D) none
7. The transistor in a circuit basically acts as: of these
(A) Voltage amplifier (B) Current amplifier 22. NOR gate is a combination of:
(C) Power amplifier (D) An oscillator (A) OR gate and NOT gate (B) OR gate and AND gate
8. The characteristics of a transistor are: (C) OR gate and OR gate (D) none of these
(A) Light dependent (B) Temperature 23. Digital circuits can be made by respective use
dependent of:
(C) Sound dependent (D) Energy (A) And gates (B) OR gates (C) NOT gates (D)
dependent NAND gates
9. Which part of the transistor is heavily 24. In NPN transistor the arrow head on emitter
doped? represents that the conventional current flows
(A) Base (B) Emitter (C) Collector (D) Both from:
base and emitter (A)Base of emitter (B) Emitter to base
10. The thickness of the base in the transistor (C) Emitter to collector (D) Base to
(C)10−6μm
is of the order of: collector
(A)10−3 m (B)10−6 m (D)106 25. How many diodes are used in a bridge rectifier?
m (A) 1 (B) 2 (C) 3 (D) 4
11. For a normal biased transistor, the emitter 26. On increasing the reverse voltage in a P-N
current is: junction diode the value of reverse current will:
(A) Equal to collector current (A) Gradually increase (B) Suddenly increase
(B) Slightly less than collector current (C) Remain constant (D) Gradually decrease
(C) Slightly greater than base current 27. The output potential in a full wave rectifier is:
(D) Slightly greater than collector current (A) Alternating (B) Fully direct (C) Fluctuating direct
12. When the base current is set zero, the (D)All of these
resistance between collector and emitter 28. On reverse biasing the P-N junction, its
becomes: potential barrier becomes:
(A) Zero (B) Infinite (C) Very low (D) (A) Narrow (B) Broad (C) Zero (D) Constant
Moderate 29. The order of magnitude of current in the
13. The phase difference between input and reverse bias connection of a junction diode is:
output of the transistor amplifier is: (A) mA (B)μA (C) A (D) KA
(A) 0° (B) 90° (C) 180° (D) 120° 30. In forward bias the depletion region behaves
14. The input resistance of the op-amp is: like:
(A) Very low (B) Very high (C) Zero (A) An insulator (B)A conductor (C) A semi-conductor
(D) Infinite (D)All above
15. An op-amp can be used as a: 31. The ratio of the resistance of a diode when
(A) Inverting amplifier (B) Night switch C) Comparator (D) connected forward biased and then reverse
All of them biased condition is:
16. The resistance of LDR increases when the (A) Less than one (B) Zero (C) Greater than 1 (D)
intensity of light Infinity
(A) Increases (B) Decreases (C) Remains constant 32. The ratio of potential barrier for Ge to Si at
(D) becomes infinite room temperature is :
17. Truth table of logic function:
(A) Summarizes its output values
3 7 2 1
(A) (B) (C) (D)
(B) Tabulates all its input conditions only 7 3 5 3
(C) Display all its input / output possibilities
1
33. PN-junction diode works as insulator if
connected:
(A) to ac source (B) in forward bias
(C) in reverse bias (D) either to ac source or in
reverse bias
34. In a PN-junction, the barrier potential offers
opposition to only:
(A) Majority carries in both region (B) Minority
carries in both regions
(C) Electrons in n-region (D) Holes in p-region
35. The P-side of a junction diode is earthed
and the n-side is given a potential
difference of -2V the diode will:
(A) Break down (B) Conduct (C) Not conduct (D)
Conduct partially
36. In a common emitter amplifier, the load
resistance is 5000 Ω and the input
resistance is 100 Ω. If the peak value of the
signal voltage is 10mV and the current
gave β is 50, then peak value of the output
voltage is:
(A)1.25 x 102 (B) 2.5 x 101 V (C) 3.75
x 10−3 V (D) 5.0 x 102 V
37. Which of the following is not characteristic
of operational amplifier?
(A) High open loop gain (B) High input
resistance
(C) High output resistance (D) Both input are
virtually at same potential
38. The unidirectional property of a PN junction
is used for its use as a/an:
(A) Transformer (B) Amplifier (C) Rectifier
(D) Oscillator
39. NPN transistors are preferred to PNP
transistors because they have:
(A) Low cost (C)Electrons have
high mobility than holes
(B) Low dissipation energy (D) Capable of handling
large power
40. Which of the following sensor can convert
changes in the intensity of light into
electric voltage:
(A) Thermistor (B) LED (C) LDR (D) Microphone
