Alternating Current Class 12 MCQ: Class 12 Physics MCQ Questions and Answer. Students get here all Important MCQ on Alternating Current Class 12.
Alternating Current Class 12 MCQ with Answers:
Multiple choice questions.
1.) The relation between Time period and frequency can be expressed as.
a) f = 1/T.
b) f = T/2
c) T = f/2.
d) f = 2T
Ans : a) f= 1/T
2.) Complete the formula.
The output V of the A.C generator is
V = V0sin (____)×t
a)2π/3.
b)2π/T
c) 2πT.
d) 2π
Ans : b) 2π/T
3.) The value of voltage or current that exists in a circuit at any instant of time t measured from some reference point is known as its ______
a) reference value.
b) instantaneous value
c) voltage value.
d) current value
Ans : b) instantaneous value
4.) The instantaneous value at time period T can be expressed as V = V0sin(___)ft
a)2π/3.
b)2π/T
c) 2πT.
d) 2π
Ans : d) 2π
5.) The highest value reached by the voltage or current in one cycle is called.
a) reference value.
b) instantaneous value
c) peak value.
d) rms value
Ans : c) peak value
6.) The sum of the position and negative peak value usually written as.
a) rms value.
b) p-p value.
c) v-v value.
d) peak value
Ans : b) p-p value
7.) The alternating current or voltage is actually measured by square root of its mean square value know as.
a) rms value.
b) p-p value
c) instantaneous value.
d) peak value
Ans : a) rms value
8.) Vrms value can be expressed as
a)√2.V0
b) 0.7 V0
c) V0/0.7
d) 0.7√V0
Ans : b) 0.7V0
9.) Complete the formula
The instantaneous current, I = I0_____
a)sinωt.
b) sinπT
c) sin2π.
d) √2π
Ans : a) sinωt
10.) The instantaneous power in the resistance can be expressed as,P = ______
a)VR.
b) V²R
c) V²/R.
d) V²/R²
Ans : c) V²/R
11.) The charge on the capacitor at any instant, can be written as.
q = ______ sinωt
a)2C.
b)CV0
c) V²R.
d) RV0
Ans : b) CV0
12.) The resistance of a capacitor can be expressed as, XC = ________
a)Irms/Vrms
b) Irms/√2
c) Vrms/√2.
d) Vrms/Irms
Ans : d) Vrms/Irms
13.) The combined effect of resistance and reactances in such a circuit is known as.
a) inductance. b) impedance
c) reactance. d) capacitance
Ans : b) impedance
14.) _______of a capacitor is a measure of the opposition offered by the capacitor to flow of A.C
a) inductance. b) impedance
c) reactance. d) capacitance
Ans : c) reactance
15.) ______ is a measure of the opposition offered by the inductance coil to the flow of A.C
a) Inductive reactance. b) Impedance
c) Capacitance. d) Root mean square value
Ans : a) Inductive reactance
16.) Inductive reactance can be expressed as. XL = _____
a)Vrms/Irms.
b) Irms/√2
c) Vrms/√2
d) Irms/Vrms
Ans : a)Vrms/Irms
17.) Impedance can be expressed as ,Z=_____
a.) √2 × Irms × Vrms
b) Vrms/ Irms
c) Vrms/√2
d) Irms /√2
Ans : b) Vrms/ Irms
18.) Complete the formula.
The current leads the applied voltage by an angle θ, then θ = ______(1/ωCR)
a)sin-1. b) cos-1
c) tan-1 d) tan
Ans : c) tan-1
19.) Power in A.C circuit can be expressed as , P = ________
a.) Irms+Vrmscosθ
b) Irms×Vrmssinθ
c) Irms×Vrmscosθ
d) Irms×Vrmstan-1θ
Ans : c) Irms×Vrmscosθ
20.) In series resonance circuit, the resonance frequency can be written as. fr =_______
a)1/2πLC
b) 1/√(2πLC)
c) 1/2π√(LC)
d) (1/2π)×√(LC)
Ans : c) 1/2π√(LC)
21.) A coil which consists of thick copper wire wound closely in a large number of turns over a soft iron laminated cores, what is it ?
a) Capacitor.
b) Magnet
c) Inductor.
d) Choke
Ans : d) Choke
22.) In free space the speed of electromagnetic wave is ,
a.) 83×108 sec
b) 3×10-8 msec-1
c) 3×108 msec-1
d) 3×1019 msec-1
Ans: c) 3×108 msec-1
23.) The relation between speed of the wave c, frequency f and wavelength λ is
a)c=fλ.
b) f= cλ
c) λ=cf
d) c=f/λ
Ans : a) c=fλ
24.) What is the name of process of combining the low frequency signal with a high frequency radio wave called carrier wave.
a) Induction.
b) Modulation
c) Transmission.
d) Conduction
Ans : b) Modulation
25.) The time interval during which the voltage source changes its polarity once is known as ______ of the alternating current or voltage.
a) Voltage V.
b) Current I
c) Period T.
d) Angleθ
Ans : c) Period T
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