MCQ
2561. Emitter follower is used for--
Impedance matching
Current gain
Voltage gain
None of the above
2562. 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.
2563. If, line frequency is 50 Hz, then output (Hz) of a bridge rectifier is-
25
100
50
None
2564. A pn junction acts as a-
unidirectional switch.
bidirecctional switch.
controlled switch.
both unidirectional and bidirectional.
2565. When there is no forbidden region between the conductance band and valence band, the substance is called:
Semiconductor.
conductor
superconductor
insulator
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. Class-B power amplifier- miximum collector efficiency কত %
25
78.5
50
60
2569. Suppose you are checking a 50 Hz full-wave bridge rectifier and observe that output has a 50 Hz ripple, then-
circuit is working properly.
trnsformer secondary is shorted.
there is an open diode.
the filter capacitor is leaky.
2570. What is the full name of LCD?
Light control diode .
Light crystal display.
Liquid crystal diode.
Liquid crystal display.
2571. At what relgon a transistor operates --
Artlive
Saturatioit
Cut off
None
2572. When the light increase, the reverse current in a photodiode-
increases
is unaffected
decreases
sometimes increases and sometimes decreases
2573. 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.
2574. ডিজিটাল রেকর্ডার কত প্রকার?
৩ প্রকার
২ প্রকার
৪ প্রকার
৫ প্রকার
2575. At absolute zero temperanre (-273°C), an intrinsic semiconductor has-
a few free electrons.
many holes.
many free electrons.
no holes or free electrons.
2576. A transistor amplifier is desired to have-- input impedance and --output imperdance.
low, high
high, high
high, low
low, low
2577. Process of adding impurities to semiconductor is called-
mixing
refining
diffusing
doping
2578. 2B. If PIV rating of a diode is exceeded-
the diode stops conduction.
the diode is destroyed.
the diode conducts heavily in the forward direction.
nothing happens.
2579. The energy band in which free electrons exist is--
first band
conduction band
second band
valence band
2580. An alternating current is converted to direct current by-
dynamo
rectifier
transformer
motor