MCQ
2561. Class-B power amplifier- miximum collector efficiency কত %
25
78.5
50
60
2562. Process of adding impurities to semiconductor is called-
mixing
refining
diffusing
doping
2563. Transistor biasing represents --conditions.
ac
both ac & dc
dc
none
2564. When there is no forbidden region between the conductance band and valence band, the substance is called:
Semiconductor.
conductor
superconductor
insulator
2565. The energy band in which free electrons exist is--
first band
conduction band
second band
valence band
2566. Half-wave rectifier- maximum efficiency--%
25
50
40.6
81.2
2567. Which one is the smallest region in a transistor?
base
collector
emitter
both (a) and (b)
2568. Emitter follower is used for--
Impedance matching
Current gain
Voltage gain
None of the above
2569. An alternating current is converted to direct current by-
dynamo
rectifier
transformer
motor
2570. At absolute zero temperanre (-273°C), an intrinsic semiconductor has-
a few free electrons.
many holes.
many free electrons.
no holes or free electrons.
2571. The primary function of a centre-tapped transformer in a power supply is to-
step up the voltage.
step down the voltage.
cause the diodes conduct alternately.
may step up or step down the voltage.
2572. If, line frequency is 50 Hz, then output (Hz) of a bridge rectifier is-
25
100
50
None
2573. When transistor is used as an amplifier, it is operated in the:
Cut off region
Saturation region
Active region
Both a and b
2574. What is the full name of LCD?
Light control diode .
Light crystal display.
Liquid crystal diode.
Liquid crystal display.
2575. The maximum efficiency of a half-wave diode rectifier is --
50%
25%
40.0%
81.2%
2576. If a power supply has no-load and full-load voltages of 30V and 25V respectively, then the percentage voltage regulation is:
10%
20%
15%
25%
2577. The arrow in the symbol of a transistor indicates the direction of-
electron current in the emitter.
electron current in the collector.
hole current in the emitter.
donor ion current.
2578. In an LC oscillator, the frequency of oscillation is:
Proportional to LC
Proportional to square root of LC
Inversely proportional to the square root of LC
Independent of the value of LC
2579. A pn junction acts as a-
unidirectional switch.
bidirecctional switch.
controlled switch.
both unidirectional and bidirectional.
2580. At what relgon a transistor operates --
Artlive
Saturatioit
Cut off
None