Questions

M.C.Q (1 Marks)

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18 questions · auto-graded multiple-choice test.

MCQ 11 Mark
In AC circuit, power is lost in only :
  • resistance
  • B
    inductance
  • C
    capacitance
  • D
    all of these
Answer
Correct option: A.
resistance
A
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MCQ 21 Mark
Mean value of alternating current in a full cycle is :
  • A
    I
  • B
    $\frac{I}{2}$
  • C
    2I
  • zero
Answer
Correct option: D.
zero
D
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MCQ 31 Mark
The phase difference between current and voltage in an A.C. circuit containing capacitance only is :
  • A
    $0^{\circ}$
  • $90^{\circ}$
  • C
    $180^{\circ}$
  • D
    $45^{\circ}$
Answer
Correct option: B.
$90^{\circ}$
B
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MCQ 41 Mark
Which quantity decrease in step-down transformer ?
  • A
    Current
  • Voltage
  • C
    Power
  • D
    Frequency
Answer
Correct option: B.
Voltage
B
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MCQ 51 Mark
In an alternating current circuit, the phase difference between current I and voltage is $\phi$ then the wattlen component of current will be :
  • A
    $I cos \phi$
  • B
    $I tan \phi$
  • $I sin \phi$
  • D
    $I cos \phi$
Answer
Correct option: C.
$I sin \phi$
C
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MCQ 61 Mark
In A.C. circuit, the current and voltage are given by $i=5 cos \omega t$ and $V=200 sin \omega t$ respectively. Power loss in the circuit is :
  • A
    20 W
  • B
    40 W
  • C
    1000 W
  • Zero
Answer
Correct option: D.
Zero
D
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MCQ 71 Mark
The relation between peack current $I_{0}$ and root mean square $I_{rms}$ is :
  • $I_{0}=\sqrt{2}I_{rms}$
  • B
    $I_{0}=I_{rms}$
  • C
    $I_{0}=2~I_{rms}$
  • D
    $I_{0}=\frac{I_{rms}}{\sqrt{2}}$
Answer
Correct option: A.
$I_{0}=\sqrt{2}I_{rms}$
A
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MCQ 81 Mark
What value of alternating current is measured by hot wire ammeter ?
  • A
    High value
  • B
    Average value
  • Root mean square value
  • D
    None of these
Answer
Correct option: C.
Root mean square value
C
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MCQ 91 Mark
If $N_{1}$ and $N_{2}$ are number of primary and secondary coils of a step-up transformer, then :
  • A
    $N_{1}>N_{2}$
  • $N_{2}>N_{1}$
  • C
    $N_{1}=N_{2}$
  • D
    $N_{1}=0$
Answer
Correct option: B.
$N_{2}>N_{1}$
B
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MCQ 101 Mark
The power factor of L-R circuit is :
  • A
    $R+\omega L$
  • $R/\sqrt{(R^{2}+\omega^{2}L^{2})}$
  • C
    $R.\sqrt{(R^{2}+\omega^{2}L^{2})}$
  • D
    $\omega L/R$
Answer
Correct option: B.
$R/\sqrt{(R^{2}+\omega^{2}L^{2})}$
B
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MCQ 111 Mark
If the phase difference between alternating current and e.m.f. is $\phi$, then the value of power factor is :
  • $cos~\phi$
  • B
    $cos^{2}\phi$
  • C
    $sin~\phi$
  • D
    $tan\phi$
Answer
Correct option: A.
$cos~\phi$
A
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MCQ 121 Mark
Impedance of L-R circuit is :
  • A
    $R^{2}+\omega^{2}L^{2}$
  • $\sqrt{(R^{2}+\omega^{2}L^{2})}$
  • C
    $R+\omega L$
  • D
    $\sqrt{R+\omega L}$
Answer
Correct option: B.
$\sqrt{(R^{2}+\omega^{2}L^{2})}$
B
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MCQ 131 Mark
The ratio of peak value and rms value of a.c. is :
  • A
    2
  • $\sqrt{2}$
  • C
    $1/\sqrt{2}$
  • D
    1/2
Answer
Correct option: B.
$\sqrt{2}$
B
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MCQ 141 Mark
An alternating electric current is represented by equation $I=0.6 sin 100 \pi t$. The frequency of alternating current is :
  • A
    $50 \pi$
  • 50
  • C
    $100 \pi$
  • D
    100
Answer
Correct option: B.
50
B
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MCQ 151 Mark
The working of dynamo is based on the principle of :
  • A
    heating effect of electric current
  • electromagnetic induction
  • C
    magnetic induction
  • D
    electric induction
Answer
Correct option: B.
electromagnetic induction
B
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MCQ 171 Mark
The peak value of voltage of an A.C. circuit is 440 V. Its virtual voltage is :
  • A
    220 V
  • B
    440 V
  • $220\sqrt{2}V$
  • D
    $440\sqrt{2}V$
Answer
Correct option: C.
$220\sqrt{2}V$
C
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MCQ 181 Mark
In an A.C. circuit the voltage is V, and current is I, then power loss will be :
  • A
    V.I
  • B
    V.I/2
  • C
    $V/\sqrt{2}$
  • depends upon the phase angle between V and I.
Answer
Correct option: D.
depends upon the phase angle between V and I.
D
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M.C.Q (1 Marks) - Physics STD 12 Science Questions - Vidyadip