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ECE Objective Questions { Diode Circuits }



50. When ym is the peak value of a full wave rectified sine wave, the average value will be
A. 0.83 ym
B. 0.717 ym
C. 0.637 ym
D. 0.5 ym

51. The rms value will be
A. 0.707 ym
B. 0.636 ym
C. 0.5 ym
D. 0.316 ym

52. The built-in potential (diffusion potential) in a p-n junction
A. is equal to the difference in the Fermi level of the two sides, expressed in volts
B. increases with the increase in the doping levels of the two sides
C. increases with the increases in temperature
D. all of these

53. A small concentration of minority carriers is injected into a homogeneous semiconductor crystal at one point. An electric field of 10V/cm is applied across the crystal and this moves the minority carriers a distances of lcm in 20p sec. The mobility (in cm2/volt sec.) of the minority carriers is
A.1,000
B.2,000
C.5,000
D.5,00,000

54. A zener diode works on the principle of
A. tunnelling of charge carriers across the junction
B. thermionic emission
C. diffusion of charge carriers across the junction
D. hopping of charge carriers across the junction

55. The depletion capacitance, C, of an abrupt p-n junction with constant doping on either side varies with reverse bias VR, as
A. Ci VR
B. C cc V -IR ,
C. Cj cc vR1/2
D. C.1 cc VR

56. The static characteristic of an adequately forward biased p-n junction is a straight line, if the plot is of
A. log I vs log V
B. log I vs V
C. I vs log V
D. I vs V

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