Question # 1

A p-n junction is formed when a crystal of silicon is growth in such a way that its one half is doped with trivalent impurity and the other half with a impurity from

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2nd group

fourth group

fifth group

sixth group

The basic circuit elements of A.C circuit are

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Resistor

Inductor

Capacitor

All the three

A resonance curve for RLC series circuit is a plot of frequency versus

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Voltage

Current

Impedance

Reactance

The value of current gain of n-p-n transistor is of the order of

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tens

hundreds

thousands

ten thousands

The output voltage of half wave rectification is in the form of

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a smooth curve

a smooth wave

pulses

all of the above

The emitter-base junction of a transistor is forward-biased and collector-base junction is reverse-biased. If the base current is increased, its

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I_cwill decrease

V_CEwill increase

I_Cwill increase

V_CCwill increase

The highest value reached by the voltage or current:

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In quarter cycle is called Instantaneous value

In half cycle is called peak-to-peak value

In one cycle is called peak value

In half cycle is called Instantaneous value

None of these

An A.C varies as a function of

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Current

Voltage

Time

Charge

When a transistor is used as a switch the circuit in which the current is to be switched OFF and ON, is connected between the

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base and emitter

collector and emitter

base and collector

any one of these

The total reactance of a series RLC circuit at resonance is

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zero

Equal to the resistance

Infinity

Capacitive

The closed loop gain of the inverting amplifier is written as

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G = R₂/R₁

G = 1 + R₂/R₁

G = -R₂/R₁

G = 1 - R₂/R₁

In series RC circuit when R=X_c, then the phase angle is

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0°

90°

70°

45°

Which of the following diode is used to derive the current in external circuit when light is incident in the circuit

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photo diode

light emitting diode

photo voltaic cell

none of these

Which of the following has a great concentration of impurity

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base

emitter

collector

none of these

When the pn-junction is forward biased. the current flows through it is of the order of

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mili-amperes

amperes

nano-amperes

micro-amperes

The r.m.s. value of alternating current is equal to its maximum value at angle of

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60°

45°

30°

90°

At resonance, the impedance of RLC series circuit is

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Maximum

Zero

Minimum

Determinate

In RLC series circuit, resonance occurs when

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X_{L > Xc}

X_{L < Xc}

X_{L = Xc}

None of these

If 250V is the RMS value of alternative voltage, then its peak value V_owill be:

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353.5V

250V

175V

zero

400V

The time interval during which the Voltage source changes its polarity once is known as:

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Time period T

Half the time period

Quarter the time period

Two third of the time period

None of these

The basic circuit element in A.C. circuits are:

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Resistor and capacitor

Resistor and Inductor

Capacitor only

Both (B) and (C)

None of these

OP-AMP has the following input terminals

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one

two

three

four

For normal operation of transistor, the batteries

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V_CCis of much lower value than V_BB

V_CCis of much higher value than V_BB

V_{CC is equal to}V_BB

none of these

In free space, the speed of electromagnetic waves is

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3 x 10⁸ms^-1

3 x 10⁶ms^-1

4 x 10⁷ms^-1

3 x 10⁹ms^-1

In n-p-n transistor, emitter base junction is kept

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reversed

forward biased

may be reversed or may be forward biased

none of these

The Instantaneous value of alternative current maybe:

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The same as its RMS value

Greater than its Rms value

The same as its peak value

Any of these

None of these

Alternating current is produced by a voltage source which polarity:

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Remains the same

Reverse after period T

Keeps on reversing with time

Reverse after every time interval T/2

Both (C) and (D)

The RMS value of alternating current is:

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0.7 times at the peak value

0.5 times the peak value

0.7 times the Instantaneous value

Equal to maximum voltage

None of these

When the emitter-base junction of a transistor is reverse biased, collector current

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Reverses

Increases

Decreases

Stops

The bridge circuit of full wave rectification uses

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one diode

two diode

three diode

four diode

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