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Online Tests
ECAT Pre General Science Physics Chapter 16 Alternating Current Online Test MCQs With Answers
Question # 1
At resonance frequency the impedance of parallel resonance circuit is
Choose an answer
Maximum
Minimum
Zero
None of the above
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Question # 2
Due to the high value of the input resistance, practically, the value of the current which flows between the input terminals is
Choose an answer
zero
small
large
very large
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Question # 3
For normal operation of transistor, the batteries
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V
CC
is of much lower value than V
BB
V
CC
is of much higher value than V
BB
V
CC is equal to
V
BB
none of these
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Question # 4
The average of A.C. current and voltage over a complete cycle is
Choose an answer
Maximum
zero
Neither zero nor maximum
None of these
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Question # 5
The waveform of alternating voltage is a:
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Square
Rectangular
Saw-tooth
Sinusoidal
None of these
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Question # 6
At resonance, the impedance of RLC series circuit is
Choose an answer
Maximum
Zero
Minimum
Determinate
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Question # 7
To design a resonant circuit of frequency 100 KHz with an inductor of inductance 5 mH, we need a capacitor of capacitance
Choose an answer
5.07 pF
50 pF
0.507 pF
507 pF
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Question # 8
In frequency modulation (FM), the carrier waves amplitude
Choose an answer
Remains constant
Increase
Decreases
None of these
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Question # 9
A signal is amplified at the output without any change of phase, if it is applied at the
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inverting input
non-inverting input
at any of the input
none of these
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Question # 10
Which of the following diode is used for the detection of light
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photo diode
light emitting diode
photo voltaic cell
all of them
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Question # 11
The phase at the positive peak of an A.C. cycle is:
Choose an answer
0
º
90
º
180
º
0 and
Ꮨ
Ꮨ/2 and 3
Ꮨ/2
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Question # 12
Unless stated otherwise, when we speak of A.C. meter reading, we usualy mean:
Choose an answer
Peak value
RMS value
Instantaneous value
Peak-to-peak value
Both (A) and (C0
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Question # 13
The device which allows only the flow of an A.C. through a circuit is
Choose an answer
Capacitor
Inductor
D.C. motor
Battery
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Question # 14
The value of current gain of n-p-n transistor is of the order of
Choose an answer
tens
hundreds
thousands
ten thousands
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Question # 15
An A.C varies as a function of
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Current
Voltage
Time
Charge
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Question # 16
In a normally biased n-p-n transistor, an electron c current I
E
flows from the
Choose an answer
emitter into the base
collector into the base
base into collector
none of these
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Question # 17
OP-AMP has the following input terminals
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one
two
three
four
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Question # 18
SI unit of impedance is
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hertz
henry
ampere
ohms
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Question # 19
In free space, the speed of electromagnetic waves is
Choose an answer
3 x 10
8
ms
-1
3 x 10
6
ms
-1
4 x 10
7
ms
-1
3 x 10
9
ms
-1
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Question # 20
The output voltage of half wave rectification is in the form of
Choose an answer
a smooth curve
a smooth wave
pulses
all of the above
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Question # 21
When the pn-junction is connected reversed biased, its resistance is of the order of
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few ohms
few kilo-ohms
few mega-ohms
few mili-ohms
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Question # 22
Electromagnetic waves transmit energy equal to
Choose an answer
1/2 mv
2
m
o
c
2
hf/c
hf
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Question # 23
During each cycle, alternating voltage reaches a peak value
Choose an answer
One time
Two times
Four times
A number of times depending on the frequency
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Question # 24
The bridge circuit of full wave rectification uses
Choose an answer
one diode
two diode
three diode
four diode
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Question # 25
Which one of the following waves belongs to electromagnetic spectrum
Choose an answer
Radio and TV waves
Radar waves
Micro waves
All of them
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Question # 26
If we connected the ordinary DC ammeter to measure alternating current, it would measure its:
Choose an answer
Instantaneous value
RMS value
Value averaged over a cycle
Either (B) or (C)
Either (A) or (C)
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Question # 27
The R
1
= infinity and R
2
= 0, then the gain of non-inverting amplifier is
Choose an answer
zero
infinity
one
any one of these
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Question # 28
Conversion of alternating current into direct current is called
Choose an answer
amplification
rectification
conduction
polarization
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Question # 29
Which one of the following Electro-magnetic wave have the highest frequency and shortest wave-length
Choose an answer
X-rays
Ultraviolet rays
y-rays
Cosmic rays
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Question # 30
Most OP-AMP operates with
Choose an answer
+
6 V supply
+
10 V supply
+
12 V supply
+
24 V supply
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Question # 31
If we connect a A.C. volt meter to read A.C. voltage, It would read its:
Choose an answer
RMS value
Instantaneous value
Valued average over a cycle
Zero
Both (B) and (C)
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