Question # 1

Conversion of alternating current into direct current is called

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amplification

rectification

conduction

polarization

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 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

The impedance of RLC series resonance circuit at resonant frequency is

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Greater than R

Equal to R

Less than R

None of these

In a transistor, the central region is called

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collector

emitter

base

none of them

The magnitude of alternative voltage V:

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Always increase

Always decrease

Remains constant

Does not remain constant

None of these

During each cycle, alternating voltage reaches a peak value

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One time

Two times

Four times

A number of times depending on the frequency

Chock consumes externally small

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Charge

Current

Power

Potential

Transmitting antenna emits

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Magnetic waves

Electric waves

Electromagnetic waves

Sound waves

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

Alternating current can be transmitted:

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To long distance

At very high cost

At very low cost

Both (A) and (C)

Both (A) and (B)

The phase angle of a series RLC circuit at resonance is

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180°

90°

0°

None of the these

Electromagnetic waves transmit energy equal to

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1/2 mv²

m_oc²

hf/c

hf

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

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

The entire wave form of sinusoidal voltage is actually a set of all the:

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Positive maximum value + V_oand negative maximum value -V_o

Posiotive maximum value +V_oand zero

Zero and negative maximum value -V_o

Any of these

None of these

The average of A.C. current and voltage over a complete cycle is

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Maximum

zero

Neither zero nor maximum

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

If we connect a A.C. volt meter to read A.C. voltage, It would read its:

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RMS value

Instantaneous value

Valued average over a cycle

Zero

Both (B) and (C)

In RLC series circuit, resonance occurs when

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X_{L > Xc}

X_{L < Xc}

X_{L = Xc}

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

The length of rotating vector (on a certain scale) represents the:

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Peak value of alternating quantity

RMS value of alternating quantity

Instantaneous value of alternating quantity

Either (B) or (C)

Either (A) or (B)

Nowadays, Most of the electric energy is produced by the A.C. generators using:

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Hydal water

Geothermal energy

Solar energy

Biomass

Both (B) and (D)

The waveform of alternating voltage is a:

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Square

Rectangular

Saw-tooth

Sinusoidal

None of these

To design a resonant circuit of frequency 100 KHz with an inductor of inductance 5 mH, we need a capacitor of capacitance

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5.07 pF

50 pF

0.507 pF

507 pF

The value of the input resistance of OP-AMP is of the order of

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few ohms

few hundred ohms

several kilo ohms

several maga ohms

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

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

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

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

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

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