Question # 1

Transmitting antenna emits

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Magnetic waves

Electric waves

Electromagnetic waves

Sound waves

The value of the potential difference across the depletion region for the case of germanium is

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0.3 V

0.5 V

0.7 V

0.9 V

A changing magnetic flux creates around itself

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An electromotive force

An electric field (changing electric flux)

Magnetic field

None of the above

Which one of the following waves belongs to electromagnetic spectrum

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Radio and TV waves

Radar waves

Micro waves

All of them

When the p-n junction is forward biased its resistance is of the order of

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few mega ohms

few kilo ohms

few ohms

few milli ohms

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 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 phase angle for RLC series resonance circuit equals

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0°

90°

180°

270°

Most OP-AMP operates with

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+ 6 V supply

+ 10 V supply

+ 12 V supply

+ 24 V supply

When the pn-junction is in reversed biased, current flows through the junction due to the

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majority carriers

minority carriers

either of them

none of them

The waveform of alternating voltage is a:

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Square

Rectangular

Saw-tooth

Sinusoidal

None of 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

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

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0°

90°

70°

45°

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

In describing functions of digital systems, a closed switch will be shown as

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0

1

low

any one of these

The input resistance of the OP-AMP is the resistance between the

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(-) input and output

(+) input and output

(-) and (+) inputs

between any inputs

Which of the following diode is used for the detection of light

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photo diode

light emitting diode

photo voltaic cell

all of them

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 amplifier which us used to perform mathematical operations electronically is known as

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calculator

OP-AMP

computer

any one of them

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

SI unit of impedance is

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hertz

henry

ampere

ohms

In half wave rectification

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both halves of the input voltage is used

only one half of the input voltage is used

either of these

none of these

The power factor of resonant series circuit is

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1

0

-1

0.5

A signal appears after amplification, at the output terminal with a phase shift of 180° , if it is applied at

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inverting input

non-inverting input

any one of the input terminal

none of them

Average value of A.C voltage during one cycle is

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1

Zero

Maximum

Variable

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 open loop gain of OP-AMP is of the order of

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10²

10³

10⁴

10⁵

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

In which of the following diodes when an electron combines with a hole during the forward biasing, photon of visible light is emitted.

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photo diode

light emitting diode

photo voltaic cell

all of them

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 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

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