Quiz: Chapter 12 - Electronics

1 A semi-conductor can be used as a rectifier because

It has low resistance to the current flow when forward biased It has high resistance to the current flow when reversed biased It has low resistance when forward biased and high resistance when reversed biased None of the above

2 The central region of a transistor is called:

Base Emitter Collector Neutral

3 The SI unit of current gain is:

Ampere Volt Ohm-meter It has no units

4 A NAND gate with two inputs A & B has an output 0 if

A is 0 B is 0 Both A and B are 0 Both A and B are 1

5 The gain G of non-inverting operational amplifier is

\( G = -\frac{R_2}{R_1} \) \( G = 1 + \frac{R_2}{R_1} \) \( G = \frac{R_2}{R_1} \) \( G = 1 - \frac{R_2}{R_1} \)

6 When a PN junction is reverse biased, the depletion region is

Widened Narrowed Normal No change

7 A potential barrier of 0.7 V exists across PN junction made from

Silicon Germanium Indium Gallium

8 A diode characteristics curve is a graph plotted between

Current and time Voltage and time Voltage and current Forward voltage and reverse current

9 The output of AND gate will be 1 when

Both inputs are at 0 Either one input is at 1 Both inputs are at 1 None of these

10 For non-inverting amplifiers if \( R_1 = \infty \) Ω and \( R_2 = 0 \) Ω, then gain of amplifier is

-1 0 +1 infinite

11 An expression for current gain of a transistor is given by

\( \beta = \frac{I_B}{I_C} \) \( \beta = I_B + I_C \) \( \beta = I_C - I_B \) \( \beta = \frac{I_C}{I_B} \)

12 In n-type materials, the minority carriers are

Free electrons Holes Protons Mesons

13 Transistors are made from

Plastics Metals Insulators Doped semi-conductors

14 The number of diodes in a bridge rectifier is

4 2 3 5

15 The reverse current through PN junction is

Infinite Zero Less than forward current Greater than forward current

16 Photocells are used for

Security system Counting system Automatic door system All of these

17 Transistor has

2 regions 3 regions 4 regions 1 region

18 A complete amplifier circuit made on a silicon chip and enclosed in a small capsule is called

Diode Inductor Resistor Operational amplifier

19 The open loop gain of an operational amplifier is of the order of

\(10^8\) \(10^5\) \(10^2\) \(10^{-3}\)

20 The automatic working of street lights is due to

Inductor Capacitor Comparator Rectifier

21 In half-wave rectification, the output DC voltage is obtained across the load for

The positive half cycle of input AC The negative half cycle of input AC Both positive and negative half cycles Either positive or negative half cycle

22 The color of light emitted by LED depends on

Its forward biased Its reversed biased The amount of forward current The type of semi-conductor material used

23 A PN junction photodiode is

Operated in forward direction Operated in reversed direction A very fast photo detector Dependent on thermally generated minority carriers

24 The reverse current through semi-conductor diode is due to

Holes Electrons Majority carriers Minority carriers

25 The potential barrier for PN junction made from Si at room temperature is

0.9 V 0.3 V 0.7 V 0.8 V

26 Process of conversion of DC to AC is called

Rectification Amplification Oscillation Modulation

27 Which one of the following is called fundamental gate

NOR gate NOT gate NAND gate Exclusive OR gate

28 For proper working of a transistor in normal circuits

Emitter-base junction is reversed biased, collector-base junction is forward biased Emitter-base junction is forward biased and collector-base junction is forward biased C-B junction is reversed biased, E-B junction is forward biased C-B junction is reversed biased and E-B junction is reversed biased

29 In a properly biased NPN transistor most of the electrons from the emitter

Recombine with holes in the base Recombine in the emitter itself Pass through the base to the collector Are stopped by the junction barrier

30 A diode characteristic curve is a graph between

Current and time Voltage and time Voltage and current Forward voltage and reverse current

31 A NOR Gate is ON only when all its input are

ON OFF Positive High

32 A logic gate is an electronic circuit which

Makes logic decision Work on binary algebra Alternates between 0 and 1 None of these

33 The output of a 2-input OR gate is zero only when its

Both input are zero Either input is 1 Both input are 1 Either input is 0

34 An XOR gate produces an positive logic output only when its two inputs are

High Low Different Same

35 An AND Gate

Implement logic addition Is equivalent to a series switching circuit Is any or all gate Is equivalent to a parallel switching circuit

36 The only function of a NOT gate is to

Stop a signal Re-complement a signal Invert an input signal Acts as a universal gate

37 The forward current through a semiconductor diode circuit is due to

Minority carriers Majority carriers Holes Electrons

38 The device used for conversion of AC into DC is

An oscillator A detector An amplifier A rectifier

39 The thickness of depletion region is of the order of

\(10^7 \, \text{m}\) \(10^6 \, \text{m}\) \(10^5 \, \text{m}\) \(10^4 \, \text{m}\)

40 The ratio of β gives the

Voltage gain Current gain Input resistance None

41 The resistance between +ive and –ive inputs of op–amplifier is

100 Ω 1000 Ω \(10^6 \, \Omega\) None of these

42 Photo-voltaic cell have

Battery input No external bias No internal bias None

43 Transistor can be used as

Oscillators Switches Memory unit All of them

44 NOT gate has only

One input Two inputs Many inputs None

45 A photo-diode can switch its current ON and OFF in

Milli seconds Micro seconds Nano seconds None

46 Diode is a device which has ______ terminals.

One Two Three Four

47 Transistor is a device which has ______ terminals.

One Two Three Four

48 The Boolean expression \(X = A + B\) represents the logic operation of

NAND gate NOR gate OR gate NOT gate

49 The open loop gain of op–amplifier is

Zero High Very high Low

50 The width of depletion region of a diode

Increases under forward bias Is independent of applied voltage Increases under reverse bias None of these

51 A LED emits lights only

Forward biased Reverse Biased Unbiased None of these

52 NAND gate is a combination

AND gate and NOT gate AND gate and OR gate OR gate and NOT gate NOT gate and NOT gate

53 The reverse or leakage current of the diode is of the order of

Microampere Milli-ampere Both None of these

54 Temperature, pressure etc are converted into electronic informations by devices called

LEDs Sensors Vacuum tubes None

55 Base of the transistor is very thin of the order of

\(10^{-2}m\) \(10^{-4}m\) \(10^{-6}m\) \(10^{-8}m\)

56 How many diodes are used for the full wave bridge rectifier circuit is

Two Three Four None of these

57 The electronic circuits which implement the various logic operations are known as

Digital gates Logic gate Voltage operated gate All of them

58 In a half-wave rectifier the diode conducts during

Both halves of the input cycle A portion of the positive half of the input cycle A portion of the negative half of the input cycle One half of the input cycle

59 The output of a two inputs OR gate is 0 only when its

Both inputs are 0 Either input is 1 Both inputs are 1 Either input is zero

60 For typical transistor as an amplifier

\(\frac{V_{out}}{V_{in}} = \beta \frac{R_C}{R_{ie}}\) \(\frac{V_{out}}{V_{in}} = \beta\) \(\frac{V_{out}}{V_{in}} = \beta \frac{R_{ie}}{R_c}\) \(\frac{V_{out}}{V_{in}} = \beta \frac{R_{ie}}{R_{ie}}\)

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Chapter 12: Electronics