# Home / ECE / Electronic Devices and Circuits :: Section 1

### ECE :: Electronic Devices and Circuits

1. At room temperature the current in an intrinsic semiconductor is due to

2.  A. holes B. electrons C. ions D. holes and electrons   3. Work function is the maximum energy required by the fastest electron at 0 K to escape from the metal surface.

4.  A. True B. False   5. The most commonly used semiconductor material is

6.  A. silicon B. germanium C. mixture of silicon and germanium D. none of the above   7. In which of these is reverse recovery time nearly zero?

8.  A. Zener diode B. Tunnel diode C. Schottky diode D. PIN diode   9. A transistor has a current gain of 0.99 in the CB mode. Its current gain in the CC mode is

10.  A. 100 B. 99 C. 1.01 D. 0.99   11. 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

12.  A. IEp and IEn are almost equal B. IEp >> IEn C. IEn >> IEp D. either (a) or (c)   13. In an n channel JFET, the gate is

14.  A. n type B. p type C. either n or p D. partially n & partially p   15. The amount of photoelectric emission current depends on

16.  A. frequency of incident radiation B. intensity of incident radiation C. both frequency and intensity of incident radiation D. none of the above   17. Assertion (A): A p-n junction has high resistance in reverse direction.

Reason (R): When a reverse bias is applied to p-n junction, the width of depletion layer increases.

18.  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   19. In the circuit of figure the function of resistor R and diode D are 20.  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.   