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A potential barrier of 0.50 V exists across a P-N junction. If the depletion region is $5.0 \times 10^{- 7}$ m wide, the intensity of the electric field in this region is

$1.0 \times 10^{6} V / m$

$1.0 \times 10^{5} V / m$

$2.0 \times 10^{5} V / m$

$2.0 \times 10^{6} V / m$

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Explanation

(a) $E = \frac{V}{d} = \frac{0.5}{5 \times 10^{- 7}} = 10^{6} V / m$

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If no external voltage is applied across P-N junction, there would be

No electric field across the junction

An electric field pointing from N-type to P-type side across the junction

An electric field pointing from P-type to N-type side across the junction

A temporary electric field during formation of P-N junction that would subsequently disappear

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Explanation

(b) Across the junction, a barrier potential is developed whose direction is from region to region.

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Barrier potential of a P-N junction diode does not depend on

Temperature

Forward bias

Doping density

Diode design

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Explanation

(d) Barrier potential does not depend upon diode design but it depends upon temperature, doping density, and forward biasing.

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Zener breakdown takes place if

Doped impurity is low

Doped impurity is high

Less impurity in N-part

Less impurity in P-type

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Explanation

(b) Zener breakdown can occur in heavily doped diodes. In lightly doped diodes the necessary voltage is higher, and avalanche multiplication is then the chief process involved.

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Which one of the following statements is not correct

A diode does not obey Ohm's law

A PN junction diode symbol shows an arrow identifying the direction of current (forward) flow

An ideal diode is an open switch

An ideal diode is an ideal one way conductor

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Explanation

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Which is the wrong statement in following sentences?

A device in which P and N-type semiconductors are used is more useful then a vacuum type because

Power is not necessary to heat the filament

It is more stable

Very less heat is produced in it

Its efficiency is high due to a high voltage across the junction

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Explanation

(d) P and N type semiconductors are stable. That's why these semiconductors have low efficiency.

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If a full wave rectifier circuit is operating from 50 Hz mains, the fundamental frequency in the ripple will be

50 Hz

70.7 Hz

100 Hz

25 Hz

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Explanation

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A diode having potential difference 0.5 V across its junction which does not depend on current, is connected in series with resistance of 20 $Ω$ across source. If 0.1 A passes through resistance then what is the voltage of the source

1.5 V

2.0 V

2.5 V

5 V

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Explanation

The given information: Potential drop across the diode = 0.5 V, Resistance = 20 Î©, Current through resistance = 0.1 A. Voltage drop across the resistance = IR = 0.1 A Ã— 20 Î© = 2 V. Total voltage of the source = Voltage drop across diode + Voltage drop across resistance = 0.5 V + 2 V = 2.5 V.

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When NPN transistor is used as an amplifier

Electrons move from base to collector

Holes move from emitter to base

Electrons move from collector to base

Holes move from base to emitter

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Explanation

(a) When NPN transistor is used as an amplifier, majority charge carrier electrons of N-type emitter move from emitter to base and than base to collector.

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The phase difference between input and output voltages of a CE circuit is

0 $°$

90 $°$

180 $°$

270 $°$

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