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

Question # 1

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 # 2

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 # 3

When the p-n junction is forward biased its resistance is of the order of

few mega ohms A
few kilo ohms B
few ohms C
few milli ohms D

Question # 4

Which of the following diode is used to derive the current in external circuit when light is incident in the circuit

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

Question # 5

A resonance curve for RLC series circuit is a plot of frequency versus

Voltage A
Current B
Impedance C
Reactance D

Question # 6

In an A.C circuit with resistor only, the current and voltage have a phase angle of

90° A
0° B
180° C
none of these D

Question # 7

The alternative voltage of current is actually measured by:

Its RMS value A
Square root of its mean square value B
Instantaneous value C
Peak value D
Both (A) and (B) E

Question # 8

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 # 9

The length of rotating vector (on a certain scale) represents the:

Peak value of alternating quantity A
RMS value of alternating quantity B
Instantaneous value of alternating quantity C
Either (B) or (C) D
Either (A) or (B) E

Question # 10

The input resistance of the OP-AMP is the resistance between the

(-) input and output A
(+) input and output B
(-) and (+) inputs C
between any inputs D

Question # 11

The phase at the positive peak of an A.C. cycle is:

0º
A
90º
B
180º
C
0 andᏘ D
Ꮨ/2 and 3Ꮨ/2 E

Question # 12

The emitter-base junction of a transistor is forward-biased and collector-base junction is reverse-biased. If the base current is increased, its

I_cwill decrease A
V_CEwill increase B
I_Cwill increase C
V_CCwill increase D

Question # 13

When electrons in the transmitting antenna vibrate 94000 time per second, they produce radiowaves having frequency

9.4 kHz A
940 kHz B
94 kHz C
None of these D

Question # 14

If 250V is the RMS value of alternative voltage, then its peak value V_owill be:

353.5V A
250V B
175V C
zero D
400V E

Question # 15

The basic circuit element in D.C. circuit is:

A capacitor A
A resistor B
An inductor C
Both (A) and (C) D
Both (A) and (B) E

Question # 16

A changing magnetic flux creates around itself

An electromotive force A
An electric field (changing electric flux) B
Magnetic field C
None of the above D

Question # 17

The magnitude of alternative voltage V:

Always increase A
Always decrease B
Remains constant C
Does not remain constant D
None of these E

Question # 18

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 # 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

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 # 21

The impedance of RLC series resonance circuit at resonant frequency is

Greater than R A
Equal to R B
Less than R C
None of these D

Question # 22

Which of the following has a great concentration of impurity

base A
emitter B
collector C
none of these D

Question # 23

The total reactance of a series RLC circuit at resonance is

zero A
Equal to the resistance B
Infinity C
Capacitive D

Question # 24

The basic circuit element in A.C. circuits are:

Resistor and capacitor A
Resistor and Inductor B
Capacitor only C
Both (B) and (C) D
None of these E

Question # 25

The circuit which is used to smooth the output voltage of the full-wave rectification is known as

transformer A
rectifier B
filter C
none of these D

Question # 26

The value of the input resistance of OP-AMP is of the order of

few ohms A
few hundred ohms B
several kilo ohms C
several maga ohms D

Question # 27

Electromagnetic waves transmit energy equal to

1/2 mv² A
m_oc² B
hf/c C
hf D

Question # 28

In n-p-n transistor, emitter base junction is kept

reversed A
forward biased B
may be reversed or may be forward biased C
none of these D

Question # 29

The Instantaneous value of alternative current maybe:

The same as its RMS value A
Greater than its Rms value B
The same as its peak value C
Any of these D
None of these E

Question # 30

An A.C varies as a function of

Current A
Voltage B
Time C
Charge D

Sr.#	Question	Answer
1	The RMS value of alternating current is:	A. 0.7 times at the peak value B. 0.5 times the peak value C. 0.7 times the Instantaneous value D. Equal to maximum voltage
2	A P-N juction or semiconductor diode cannot be used as	A. A rectifier B. Detector C. Oscillator D. An amplifier
3	When the pn-junction is connected reversed biased, its resistance is of the order of	A. few ohms B. few kilo-ohms C. few mega-ohms D. few mili-ohms
4	The basic circuit element in A.C. circuits are:	A. Resistor and capacitor B. Resistor and Inductor C. Capacitor only D. Both (B) and (C)
5	The length of rotating vector (on a certain scale) represents the:	A. Peak value of alternating quantity B. RMS value of alternating quantity C. Instantaneous value of alternating quantity D. Either (B) or (C)
6	To design a resonant circuit of frequency 100 KHz with an inductor of inductance 5 mH, we need a capacitor of capacitance	A. 5.07 pF B. 50 pF C. 0.507 pF D. 507 pF
7	The value of output resistance of OP-AMOP is of the order of	A. few ohms B. few hundred ohms C. several kilo ohms D. several mega ohms
8	In a transistor, if the central region is n-type, then this type of transistor is known as	A. n-p-n transistor B. p-n-p transistor C. either of these D. none of these
9	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
10	Chock consumes externally small	A. Charge B. Current C. Power D. Potential

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