A transistor has a current gain of 0.99 in the CB mode. Its current gain in the

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Question
A transistor has a current gain of 0.99 in the CB mode. Its current gain in the CC mode is
Options
A. 100
B. 99
C. 1.01
D. 0.99

Correct Answer

100

Explanation

A transistor has a current gain of 0.99 in the CB mode. Its current gain in the CC mode is 100 99 1.

Current gain = 1 + ? = 100.

Electronic Devices and Circuits problems

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1. A transistor has two p-n junctions. The batteries should be connected such that
Options
A. both junctions are forward biased
B. both junctions are reverse biased
C. one junction is forward biased and the other is reverse biased
D. none of the above

2. Assertion (A): The conductivity of p type semiconductor is higher than that of intrinsic semiconductor.
Reason (R): The addition of donor impurity creates additional energy levels below conduction band.
Options
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

3. In a bipolar transistor which current is largest
Options
A. collector current
B. base current
C. emitter current
D. base current or emitter current

4. In the circuit of figure the function of resistor R and diode D are
Options
A. to limit the current and to protect LED against over voltage
B. to limit the voltage and to protect LED against over current
C. to limit the current and protect LED against reverse breakdown voltage.
D. none of the above.

5. At room temperature the current in an intrinsic semiconductor is due to
Options
A. holes
B. electrons
C. ions
D. holes and electrons

6. A p-n junction diode has
Options
A. low forward and high reverse resistance
B. a non-linear v-i characteristics
C. zero forward current till the forward voltage reaches cut in value
D. all of the above

7. Assertion (A): The reverse saturation current in a semiconductor diode is 4nA at 20�C and 32 nA at 50�C.
Reason (R): The reverse saturation current in a semiconductor diode doubles for every 10�C rise in temperature.
Options
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

8. Calculate the stability factor and change in I_C from 25�C to 100�C for, ? = 50, R_B/ R_E = 250, ?I_C0 = 19.9 nA for emitter bias configuration.
Options
A. 42.53, 0.85 ?A
B. 40.91, 0.58 ?A
C. 40.91, 0.58 ?A
D. 41.10, 0.39 ?A

10. An amplifier without feedback has a voltage gain of 50, input resistance of 1 k? and output resistance of 2.5 k?. The input resistance of the current shunt -ve feedback amplifier using the above amplifier with a feedback factor of 0.2 is
Options
A. 1/11 k?
B. 1/5 k?
C. 5 kW
D. 11 kW

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