MCQ 11 Mark
Frequency of electric current in alternating current I $=200 \sin \left(60 \pi t+\frac{\pi}{6}\right)$ is :
- A120 Hz
- B60 Hz
- C90 Hz
- ✓30 Hz
Answer
View full question & answer→Correct option: D.
30 Hz
(d)30 Hz
Questions
M.C.Q (1 Marks)
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Test yourself on this topic
29 questions · timed · auto-graded
MCQ 21 Mark
The number of turns in primary and secondary coils of a transformer are 100 and 300 respectively. If in- put power is 60 W, then output power will be:
- ✓60 W
- B20 W
- C180 W
- DNone of these
Answer
View full question & answer→Correct option: A.
60 W
(a)60 W
MCQ 31 Mark
A transformer increases ac voltage supply from 220 V to 2200 V. If there are 2000 turns in the second- ary coil, then number of turns in the primary coil is:
- A100
- B50
- ✓200
- D30
Answer
View full question & answer→Correct option: C.
200
(c)200
MCQ 41 Mark
Which of the following substance is most suitable to make core of transformer?
- ✓Soft iron
- BNickel
- CCopper
- DStainless steel
Answer
View full question & answer→Correct option: A.
Soft iron
(a)Soft iron
MCQ 51 Mark
Potential difference in ac circuit is $V =20 \sin \omega t$ and current flowing is $I =5 \cos \omega t$, then power dissipated in watts is :
- ✓0
- B10
- C5
- D100
Answer
View full question & answer→Correct option: A.
0
(a)0
MCQ 61 Mark
A lamp whose resistance is $280 \Omega$ is joined with an ac source of 200 V . The peak value of current flowing in the lamp is :
- ✓1.0 A
- B2.0 A
- C0.7 A
- D1.4 A
Answer
View full question & answer→Correct option: A.
1.0 A
(a)1.0 A
MCQ 71 Mark
In an ac circuit, phase of current lags the phase of voltage by an angle of $\frac{\pi}{3}$. The component in the circuit is :
- AL and C
- ✓R and I
- CR and C
- DOnly R
Answer
View full question & answer→Correct option: B.
R and I
(b)R and I
MCQ 81 Mark
Magnitude of current at half power point in a circuit is:
- A$I _{\max } \sqrt{2}$
- ✓$\frac{I_{\max }}{\sqrt{2}}$
- C$2 I _{\max }$
- D$\frac{I_{\max }}{2}$
Answer
View full question & answer→Correct option: B.
$\frac{I_{\max }}{\sqrt{2}}$
(b)$\frac{I_{\max }}{\sqrt{2}}$
MCQ 91 Mark
Resistance of a circuit is $12 \Omega$ and impedance is $15 \Omega$. The power factor of the circuit is :
- A0.4
- ✓0.8
- C0.125
- D1.25
Answer
View full question & answer→Correct option: B.
0.8
(b)0.8
MCQ 101 Mark
Phase difference between voltage across the ends of an inductor coil and capacitor in radians is:
- ✓$\pi$
- B$\frac{\pi}{2}$
- CZero
- D$2 \pi$
Answer
View full question & answer→Correct option: A.
$\pi$
(a)$\pi$
MCQ 111 Mark
Phase difference between ac current and emf is $\frac{\pi}{2}$.Which of the following cannot be a component of the circuit?
- AL, C
- BOnly L
- COnly C
- ✓R, L
Answer
View full question & answer→Correct option: D.
R, L
(d)R, L
MCQ 121 Mark
An electric heater is heated by de and ac respec- tively. The potential difference applied across the ends of heater for both ac and de is same. Heat gener- ated per second will be more:
- AOn heating with ac
- BOn heating with de
- ✓Same in both
- DNone of the above two
Answer
View full question & answer→Correct option: C.
Same in both
(c)Same in both
MCQ 131 Mark
Magnitude of potential difference across L. C and R in a series LCR circuit is 100 V. If resistor is re- moved, then magnitude of current in the circuit is:
- AZero
- ✓Infinite
- C10 A
- D20 A
Answer
View full question & answer→Correct option: B.
Infinite
(b)Infinite
MCQ 141 Mark
Peak value of applied alternating voltage in a LR cir- cuit is 5 V. If magnitude of maximum voltage across the ends of resistor is 3 V. then maximum value of voltage across the inductor is
- A2 V
- ✓4 V
- C$5 \sqrt{2} V$
- DZero
Answer
View full question & answer→Correct option: B.
4 V
(b)4 V
MCQ 151 Mark
Power factor of LCR circuit in resonance is:
- A0
- B0.5
- ✓1
- DDepends on values of L, C and R.
Answer
View full question & answer→Correct option: C.
1
(c)1
MCQ 161 Mark
Impedance of a circuit of inductance L and resis- tance R is denoted by:
- ALR
- B$\frac{ L }{ R }$
- ✓$\sqrt{L^2 \omega^2+R^2}$
- D$\sqrt{ R ^2 \omega^2+ L ^2}$
Answer
View full question & answer→Correct option: C.
$\sqrt{L^2 \omega^2+R^2}$
(c)$\sqrt{L^2 \omega^2+R^2}$
MCQ 171 Mark
A pure resistor is joined with a capacitor. The magni- tude of tangent of their phase difference in the cir- cuit is:
- A$C \omega / R$
- B$R / C \omega$
- ✓$1 / C \omega/R$
- D$C \omega R$
Answer
View full question & answer→Correct option: C.
$1 / C \omega/R$
(c)$1 / C \omega/R$
MCQ 181 Mark
Resistance of capacitor for high frequency is:
- AHigh
- ✓Low
- CZero
- DNone of these
Answer
View full question & answer→Correct option: B.
Low
(b)Low
MCQ 191 Mark
The point representing reso- nant condition in the figure given is:
- ✓A
- BB
- CC
- DD
Answer
View full question & answer→Correct option: A.
A
(a)A
MCQ 201 Mark
In an ac circuit, potential differenc is $V =10 \cos \omega t$ and current flowing through is $I =2 \sin \omega t$ then magnitude of power dissipated is :
- ✓Zero
- B10 W
- C5 W
- D1.25 W
Answer
View full question & answer→Correct option: A.
Zero
(a)Zero
MCQ 211 Mark
An electric bulb is made to work at 12 V dc. When this bulb is joined with an ac source, it gives normal brightness. Peak voltage of ac source is:
- A12 V
- ✓17 V
- C24 V
- D8.4 V
Answer
View full question & answer→Correct option: B.
17 V
(b)17 V
MCQ 221 Mark
A direct current of 4 A is flowing through any circuit. Root mean square value of the current is:
- ✓4 A
- B$\frac{4}{\sqrt{2}} A$
- C$4 \sqrt{2} A$
- DThere is no root mean square value of direct current.
Answer
View full question & answer→Correct option: A.
4 A
(a)4 A
MCQ 231 Mark
Root mean square value of ac voltage $V=$ $200 \sin \left(100 \pi t+\frac{\pi}{2}\right)$ is :
- ✓$100 \sqrt{2} V$
- B$200 \sqrt{2} V$
- C200 V
- D100 V
Answer
View full question & answer→Correct option: A.
$100 \sqrt{2} V$
(a)$100 \sqrt{2} V$
MCQ 241 Mark
Alternating current is produced in:
- ATransformers
- BChoke coil
- ✓Dynamo
- DBattery
Answer
View full question & answer→Correct option: C.
Dynamo
(c)Dynamo
MCQ 251 Mark
L, C and R represent physical quantities-inductance, capacitance and resistance respectively. The one which has same dimensions as time is:
- A$\frac{ C }{ L }$
- B$\frac{1}{ RC }$
- ✓$\frac{ L }{ R }$
- D$\frac{ RL }{ C }$
Answer
View full question & answer→Correct option: C.
$\frac{ L }{ R }$
(c)$\frac{ L }{ R }$
MCQ 261 Mark
Maximum value of voltage in an ac circuit is 282 V. The effective magnitude of voltage is:
- ✓200 V
- B300 V
- C400 V
- D564 V
Answer
View full question & answer→Correct option: A.
200 V
(a)200 V
MCQ 271 Mark
In an ac circuit, current $I=5 \sin \left(100 t-\frac{\pi}{2}\right)$ ampere and altemating potential difference is $V =200$ sin ( 100 t ). The power dissipated in the circuit is :
- A1000 W
- ✓Zero W
- C40 W
- D20 W
Answer
View full question & answer→Correct option: B.
Zero W
(b)Zero W
MCQ 281 Mark
Alternating current cannot be measured by de ammeter because:
- AAlternating current does not pass through ammeter.
- ✓Average value of current for a complete cycle is zero.
- CSome part of alternating current does not pass through ammeter.
- DNone of the above
Answer
View full question & answer→Correct option: B.
Average value of current for a complete cycle is zero.
(b)Average value of current for a complete cycle is zero.
MCQ 291 Mark
Frequency and potential difference of AC sent to homes in India is:
- ✓50 Hz, 220 V
- B60 Hz, 220 V
- C60 Hz, 110 V
- D50 Hz, 110 V
Answer
View full question & answer→Correct option: A.
50 Hz, 220 V
(a)50 Hz, 220 V