Question # 1

The most common source of alternating voltage is:

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Motor

Transformer

AC genrator

Both (A) and (C)

Both (A) and (B)

In an A.C circuit with resistor only, the current and voltage have a phase angle of

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90°

0°

180°

none of these

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

In which of the following components, pn-junction is used

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light emitting diode

photo diode

photo voltaic cell

all of these

A digital system deals with quantities or variables which have

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only one state

only two discrete states

three discrete states

four discrete states

The power factor of resonant series circuit is

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1

0

-1

0.5

When electrons in the transmitting antenna vibrate 94000 time per second, they produce radiowaves having frequency

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9.4 kHz

940 kHz

94 kHz

None of these

An A.C. voltmeter read 250 volts. The frequency of alternating is 50 Hz, the peak value of voltage is

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3525.0 volts

35.35 volts

353.5 volts

3.535 volts

At resonance, the impedance of RLC series circuit is

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Maximum

Zero

Minimum

Determinate

For a n-p-n transistor, the conventional current equation can be written as

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I_E+ I_C= I_B

I_C- I_B= I_E

I_C+ I_B= I_E

I_B+ I_E= I_C

The total reactance of a series RLC circuit at resonance is

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zero

Equal to the resistance

Infinity

Capacitive

If we connected the ordinary DC ammeter to measure alternating current, it would measure its:

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Instantaneous value

RMS value

Value averaged over a cycle

Either (B) or (C)

Either (A) or (C)

The phase at the positive peak of an A.C. cycle is:

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0º

90º

180º

0 andᏘ

Ꮨ/2 and 3Ꮨ/2

The sum of positive and negative peak values is called:

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Instantaneous value

Peak value

Rms valuie

Peak-to peak-value

None of these

The waveform of alternating voltage is a:

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Square

Rectangular

Saw-tooth

Sinusoidal

None of these

The phase angle of a series RLC circuit at resonance is

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180°

90°

0°

None of the these

If the value of C in a series RLC circuit is increased, the resonant frequency

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Is not affected

Increase

Remains the same

Decreases

A sinusoidally alternating voltage or current can be graphically represented by a:

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Vector

Rotating vector

Clockwise vector

Anticlockwise voltage vector

None of these

The wave form of alternating voltage is the graph between:

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Voltage across X-axis and time across y-axis

Current and time

Voltage along y-axis and time along x-axis

Voltage and current

Either (B) or (D)

At resonance frequency the impedance of parallel resonance circuit is

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Maximum

Minimum

Zero

None of the above

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

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Reverses

Increases

Decreases

Stops

During the positive half-cycle in the half-wave rectification,the diode

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does not conduct

conducts

either of these

neither of these

When the pn-junction is connected reversed biased, its resistance is of the order of

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few ohms

few kilo-ohms

few mega-ohms

few mili-ohms

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

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

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

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60°

45°

30°

90°

In RLC series circuit, resonance occurs when

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X_{L > Xc}

X_{L < Xc}

X_{L = Xc}

None of these

A diode characteristic curve is a plot between

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current and time

voltage and time

voltage and current

forward voltage and reversed voltage

The value of output resistance of OP-AMOP is of the order of

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few ohms

few hundred ohms

several kilo ohms

several mega ohms

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