22. Heaters for vacuum tubes normally take a voltage of
A. 1 V
B. 2.3 V
C. 6.3 V
D. 220 V
23. The capacitance of a reverse biased PN-junction
A. increases as the reverse bias is de creased
B. increases as the reverse bias is increased
C. depends mainly on the reverse saturation current
D. makes the PN-junction more effective at high frequencies
24. A power supply with a dc outputof 140 V has a 60 Hz ripple of 1.4 V. What is the percentage ripple?
A.0.10%
B.0.14%
C.1%
D.2.40%
25. PN-junction is heavily doped in case of
A. PIN diodes
B. Tunnel diodes
C. Gundiodes
D. All of the above
26. The internal voltage drop in case of vacuum tube diode is of the order of
A. 1 to 2 volts
B. 2 to 5 volts
C. 5 to 10 volts
D. 15 to 20 volts
27. The internal voltage drop in case of silicon diodes is around
A. 1 to 2 volts
B. 2 to 5 volts
C. 5 to 10 volts
D. 10 to 20 volts
28. A semi-conductor diode when tested with ohmeter gives low value of R in both directions, hereforeit can be concluded that
A. the diode is shorted
B. the diode is open
C. the diode is satisfactory
D. nothing can be concluded on the basis of information provided
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