ECAT Pre General Science Chapter 16 online mcq test with answers for Physics chapter 16 (Alternating Current)

Question # 1

Electromagnetic waves transmit energy equal to

1/2 mv² A
m_oc² B
hf/c C
hf D

Question # 2

The wave form of alternating voltage is the graph between:

Voltage across X-axis and time across y-axis A
Current and time B
Voltage along y-axis and time along x-axis C
Voltage and current D
Either (B) or (D) E

Question # 3

The basic circuit elements of A.C circuit are

Resistor A
Inductor B
Capacitor C
All the three D

Question # 4

Alternating current can induce voltage because it has a

High peak value A
Varying magnetic field B
Stronger field than direct curren C
Constant magnetic field D

Question # 5

When the pn-junction is in reversed biased, current flows through the junction due to the

majority carriers A
minority carriers B
either of them C
none of them D

Question # 6

In which of the following diodes when an electron combines with a hole during the forward biasing, photon of visible light is emitted.

photo diode A
light emitting diode B
photo voltaic cell C
all of them D

Question # 7

The waveform of alternating voltage is a:

Square A
Rectangular B
Saw-tooth C
Sinusoidal D
None of these E

Question # 8

In a transistor, the central region is called

collector A
emitter B
base C
none of them D

Question # 9

The closed loop gain of the inverting amplifier is written as

G = R₂/R₁ A
G = 1 + R₂/R₁ B
G = -R₂/R₁ C
G = 1 - R₂/R₁ D

Question # 10

When the pn-junction is connected reversed biased, its resistance is of the order of

few ohms A
few kilo-ohms B
few mega-ohms C
few mili-ohms D

Question # 11

The output voltage of half wave rectification is in the form of

a smooth curve A
a smooth wave B
pulses C
all of the above D

Question # 12

The device which allows only the flow of an A.C. through a circuit is

Capacitor A
Inductor B
D.C. motor C
Battery D

Question # 13

The sum of positive and negative peak values is called:

Instantaneous value A
Peak value B
Rms valuie C
Peak-to peak-value D
None of these E

Question # 14

A sinusoidally alternating voltage or current can be graphically represented by a:

Vector A
Rotating vector B
Clockwise vector C
Anticlockwise voltage vector D
None of these E

Question # 15

When either L or C is increased, the resonant frequency of the RLC series circuit

Increases A
Decreases B
Remains the same C
Becomes zero D

Question # 16

Due to the high value of the input resistance, practically, the value of the current which flows between the input terminals is

zero A
small B
large C
very large D

Question # 17

Which one of the following Electro-magnetic wave have the highest frequency and shortest wave-length

X-rays A
Ultraviolet rays B
y-rays C
Cosmic rays D

Question # 18

In half wave rectification

both halves of the input voltage is used A
only one half of the input voltage is used B
either of these C
none of these D

Question # 19

Which of the following diodes can operate in the reverse biased condition

photo diode A
light emitting diode B
photo voltaic cell C
none of these D

Question # 20

Transmitting antenna emits

Magnetic waves A
Electric waves B
Electromagnetic waves C
Sound waves D

Question # 21

The most common source of alternating voltage is:

Motor A
Transformer B
AC genrator C
Both (A) and (C) D
Both (A) and (B) E

Question # 22

The value of current gain of n-p-n transistor is of the order of

tens A
hundreds B
thousands C
ten thousands D

Question # 23

During each cycle, alternating voltage reaches a peak value

One time A
Two times B
Four times C
A number of times depending on the frequency D

Question # 24

In RLC series circuit, resonance occurs when

X_{L > Xc} A
X_{L < Xc} B
X_{L = Xc} C
None of these D

Question # 25

In describing functions of digital systems, a closed switch will be shown as

0 A
1 B
low C
any one of these D

Question # 26

For normal operation of transistor, the batteries

V_CCis of much lower value than V_BB A
V_CCis of much higher value than V_BB B
V_{CC is equal to}V_BB C
none of these D

Question # 27

In which of the following components, pn-junction is used

light emitting diode A
photo diode B
photo voltaic cell C
all of these D

Question # 28

The bridge circuit of full wave rectification uses

one diode A
two diode B
three diode C
four diode D

Question # 29

The RMS value of alternating current is:

0.7 times at the peak value A
0.5 times the peak value B
0.7 times the Instantaneous value C
Equal to maximum voltage D
None of these E

Question # 30

At resonance, the phase angle for RLC series resonance circuit equals

0° A
90° B
180° C
270° D

Sr.#	Question	Answer
1	An A.C. voltage is applied across the inductor. When the frequency of the voltage is increased, the current	A. Decreases B. Increases C. Does not change D. Momentarily goes to zero
2	Which of the following diodes can operate in the reverse biased condition	A. photo diode B. light emitting diode C. photo voltaic cell D. none of these
3	The phase at the positive peak of an A.C. cycle is:	A. 0º B. 90º C. 180º D. 0 andᏘ
4	SI unit of impedance is	A. hertz B. henry C. ampere D. ohms
5	When a transistor is used as a switch the circuit in which the current is to be switched OFF and ON, is connected between the	A. base and emitter B. collector and emitter C. base and collector D. any one of these
6	A resonance curve for RLC series circuit is a plot of frequency versus	A. Voltage B. Current C. Impedance D. Reactance
7	The output voltage of half wave rectification is in the form of	A. a smooth curve B. a smooth wave C. pulses D. all of the above
8	Alternating current is produced by a voltage source which polarity:	A. Remains the same B. Reverse after period T C. Keeps on reversing with time D. Reverse after every time interval T/2
9	Most OP-AMP operates with	A. + 6 V supply B. + 10 V supply C. + 12 V supply D. + 24 V supply
10	If we connected the ordinary DC ammeter to measure alternating current, it would measure its:	A. Instantaneous value B. RMS value C. Value averaged over a cycle D. Either (B) or (C)

Latest Educational News Stories

Pakistan's Largest Database of Colleges and Universities

BS Programs

University Past Papers

University Results

Exam Results 2024

Study Abroad Programs and Opportunities for Pakistani Students

ECAT Pre General Science Physics Chapter 16 MCQ Test With Answer

MCQ's Test For ECAT Pre General Science Physics Chapter 16 Alternating Current

ECAT Pre General Science Physics Chapter 16 Alternating Current