## Electronic Devices and Circuits problems

• 1. A zener diode is used in

• Options
• A. voltage regulator circuit
• B. amplifier circuits
• C. both voltage regulator and amplifier circuit
• D. none of the above
• 2. In an n-p-n transistor, the majority carriers in the base are

• Options
• A. electrons
• B. holes
• C. both holes and electrons
• D. either holes or electrons
• 3. In p-n-p transistor the current IE has two components viz. IEP due to injection of holes from p-region to n-region and IE due to injection of electrons from n-region to p-region. Then

• Options
• A. IEp and IEn are almost equal
• B. IEp >> IEn
• C. IEn >> IEp
• D. either (a) or (c)
• 4. The amount of photoelectric emission current depends on

• Options
• A. frequency of incident radiation
• B. intensity of incident radiation
• C. both frequency and intensity of incident radiation
• 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. 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.
• 7. In a bipolar transistor which current is largest

• Options
• A. collector current
• B. base current
• C. emitter current
• D. base current or emitter current
• 8. 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
• 9. 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
• 10. 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