Electronic Devices and Circuits - Section 1 (4)

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Electronic Devices and Circuits - Section 1

25.

Crossover distortion behaviour is characteristic of

A.	class A O/P stage
B.	class B O/P stage
C.	class AB output stage
D.	common pulse O/P state

Answer: Option B

Explanation:

It is a characteristics of class B output stage as the amplifier is biased in cut-off region.

In class B amplifier, two transistor are operated in such a way that one is amplify the half cycle and second is amplify -ve half cycle.

76-381-1

26.

As compared to an ordinary semiconductor diode , a Schottky diode

A.	has higher reverse saturation current
B.	has higher reverse saturation current and higher cut in voltage
C.	has higher reverse saturation current and lower cut in voltage
D.	has lower reverse saturation current and lower cut in voltage

Answer: Option C

Explanation:

This is due to high electron concentration in metals.

27.

Assertion (A): When a high reverse voltage is applied to a p-n junction the diode breaks down.

Reason (R): High reverse voltage causes Avalanche effect.

A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not a correct explanation of A
C.	A is true but R is false
D.	A is false but R is true

Answer: Option A

Explanation:

Avalanche breakdown occurs at high reverse voltage.

28.

As compared to an ordinary semiconductor diode, a Schottky diode

A.	has lower cut in voltage
B.	has higher cut in voltage
C.	lower reverse saturation current
D.	both (b) and (c)

Answer: Option A

Explanation:

Cut in voltage in Schottky diode is about 0.3 V as compared to 0.7 V in ordinary semiconductor diode.

29.

An amplifier without feedback has a voltage gain of 50, input resistance of 1 kΩ and output resistance of 2.5 kΩ. The input resistance of the current shunt -ve feedback amplifier using the above amplifier with a feedback factor of 0.2 is

A.	1/11 kΩ
B.	1/5 kΩ
C.	5 kW
D.	11 kW

Answer: Option A

Explanation:

Input Resistance with feedback for current shunt, 76-401-1

30.

Recombination produces new electron-hole pairs

A.	True
B.	False

Answer: Option B

Explanation:

Due to recombination the number of electron-hole pairs is reduced.

31.

In a bipolar transistor the barrier potential

A.	0
B.	a total of 0.7 V
C.	0.7 V across each depletion layer
D.	0.35 V

Answer: Option C

Explanation:

Since there are two p-n junctions, there are two depletion layers and 0.7 V across each layer.

32.

A silicon (PN) junction at a temperature of 20°C has a reverse saturation current of 10 pico Ampere. The reverse saturation current at 40°C for the same bias is approximately.

A.	30 pA
B.	40 pA
C.	50 pA
D.	60 pA

Answer: Option B

Explanation:

By increasing of temperature by 10°C, Io become double so by increasing temperature 20°C, Io become 4 time than initial value... and it is 40 PA.

Electronic Devices and Circuits - Section 1 (4)

Electronic Devices and Circuits - Section 1

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