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#### Electromagnetic Induction and Alternating Current One Mark Questions

12th Standard EM

Reg.No. :
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Physics

Time : 00:30:00 Hrs
Total Marks : 15
10 x 1 = 10
1. In a series resonant RLC circuit, the voltage across 100 Ω resistor is 40 V. The resonant frequency ω is 250 rad/s. If the value of C is 4 μF, then the voltage across L is

(a)

600 V

(b)

4000 V

(c)

400 V

(d)

1 V

2. An inductor 20 mH, a capacitor 50 μF and a resistor 40 Ω are connected in series across a source of emf v = 10 sin 340 t. The power loss in AC circuit is

(a)

0.76 W

(b)

0.89 W

(c)

0.46 W

(d)

0.67 W

3. The instantaneous values of alternating current and voltage in a circuit are $i=\frac { 1 }{ \sqrt { 2 } } sin\left( 100\pi t \right)$ A and v=$=\frac { 1 }{ \sqrt { 2 } } sin\left( 100\pi t+\frac { \pi }{ 3 } \right) V.$The average power in watts consumed in the circuit is

(a)

$\frac{1}{4}$

(b)

$\frac{\sqrt3}{4}$

(c)

$\frac{1}{2}$

(d)

$\frac{1}{8}$

4. In an oscillating LC circuit, the maximum charge on the capacitor is Q. The charge on the capacitor when the energy is stored equally between the electric and magnetic fields is

(a)

$\frac{Q}{2}$

(b)

$\frac{Q}{\sqrt3}$

(c)

$\frac{Q}{\sqrt2}$

(d)

Q

5. $\frac{20}{\pi^2}H$inductor is connected to a capacitor of capacitance C. The value of C in order to impart maximum power at 50 Hz is

(a)

50 μF

(b)

0.5 μF

(c)

500 μF

(d)

5 μF

6. In LCR series circuit, at resonance is ___________

(a)

impedance (Z) is maximum

(b)

current is minimum

(c)

impedance (Z) is equal to R

(d)

vo = $\frac{1}{LC}$

7. In a LCR series a.c, circuit, the phase difference between current and voltage is 60°. If the net reactance of the circuit is 17.32Ω, the value of the resistance is

(a)

30Ω

(b)

17.32 Ω

(c)

10 Ω

(d)

1.732 Ω

8. The average power consumed per cycle is:

(a)

Zero

(b)

2000 W

(c)

1000 W

(d)

500 W

9. The instantaneous current in an AC circuit containing a pure inductor is i = Io sinωt, The instantaneous emf is: The

(a)

e = Eosin$\left( \omega t+\frac { \pi }{ 2 } \right)$

(b)

e = Eosin$\left( \omega t-\frac { \pi }{ 2 } \right)$

(c)

e=Eosin(ωt - π)

(d)

e = Eosin

10. In RLC series AC circuit at resonance:

(a)

Resistance is zero

(b)

Net reactance is zero

(c)

impedance is maximum

(d)

voltage leads the current by a phase angle $\frac{ㅠ}{2}$

11. 5 x 1 = 5

13. (1)

Voltage and current are in phase

14. Ac circuit with resistor

15. (2)

Predominantly Inductive

16. Ac circuit with inductor

17. (3)

18. Ac circult with capacitor

19. (4)

20. RLC circuit

21. (5)

Electromagnetic Induction