Semiconductors and Electronic Devices Test

Result

Semiconductors and Electronic Devices Test - 9

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Weekly Quiz Competition

Question 1
1 / -0.25

Which of the following is not an ac parameter of a transistor?

A
Power factor

B
Current amplification factor

C
Input resistance

D
Output resistance

Solution

Input resistance, Output resistance and Current amplification factor are ac parameters of a transistor.
Question 2
1 / -0.25

What is the voltage gain in a common emitter, where input resistance is 3 Ωand the load resistance is 24 Ω, β= 0.6

A
2.4

B
8.4

C
4.8

D
480

Solution

Voltage gain =β×(R_c /R_b )
Or, Voltage gain =0.6 ×(24/3)=4.8
Question 3
1 / -0.25

An oscillator is nothing but an amplifier with:

A
positive feedback

B
No feedback

C
Negative feedback

D
Reverse feedback

Solution

An oscillator is an electronic circuit that converts DC from a power supply to an AC signal. An oscillator produces a periodic and oscillating signal. An oscillator is like an amplifier that gives positive feedback to the circuit. Positive feedback means that a portion of output is combined in phase with the input.
Question 4
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The output characteristic for a common emitter transistor is shown in the given figure.
Use the graph to find out the current amplification factor for the transistor when V_CE = 2 V.

A
10

B
zero

C
100

D
1000
Question 5
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The power amplification for a common emitter (CE) amplifier is 22110. Its current gain is 67 and internal resistance is 200 ohm. What is the value of the of the output resistance?

A
985 ohm

B
66000 ohm

C
41 ohm

D
9125 ohm

Solution
Question 6
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A common emitter (CE) amplifier has a current gain of 49. The voltage drop across the collector terminal is 1.8 V. The collector resistance is 2.2 kilo-ohm. What is the base current in the CE amplifier?

A
1.41 x 10^-5 A

B
1.81 x 10^-5 A

C
1.27 x 10^-5 A

D
1.67 x10^-5 A

Solution

Given,
Current gain(B)=4g
Voltage drop across terminal
Collector=1.8v
Collector resistance=2.2k Ω
Collector current=1.8/2.2x10³
Current gain=△I_C /△I_B
△I_B =1.8/2.2x103x4g
(D)△I_B =1.67x10^-5 A
Question 7
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Which of the following relations correctly shows the value of current amplification factor at a constant collector-emitter voltage?

A

B

C

D
Question 8
1 / -0.25

Transistors are useful in equipments such as hearing aids and small radio receivers because transistors :

A
do not distort sound

B
Can stand rough use

C
Consume little power

D
Are inexpensive

Solution

Transistors consume very less energy and are therefore used in these equipment because these equipment don 't have space for big power source.
Question 9
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The input voltage applied to a cascaded amplifier (consisting of two amplifiers) is 0.02 V and the output voltage is 6 V. The voltage gain of one of the two amplifiers is 10. What is the voltage gain of the other amplifier?

A
1/30

B
30

C
3

D
1/3
Question 10
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In a common base transistor circuit, the current gain is 0.98. On changing emitter current by 5 mA, the change in collector current is

A
0.196 mA

B
2.45 mA

C
4.9 mA

D
5.1 mA

Solution

Given, That the current gain is 0.98
The change in emitter current is I_e =5mA
Therefore, the change in collector current is I_c =0.98 ×I_e =0.98 ×5=4.9mA
Therefore, the correct option is C.