Physics

1. A coil has an inductance of 0.7 Henry and is joined in series with a resistance of 220 Ω. When the alternating emf of 220 V at 50 Hz is applied to it then the phase through which current lags behind the applied emf and the wattles component of current in the circuit will be respectively

60°, 1.5 A

30°, 1A

None of these

45°, 0.5 A

Question 1 of 15

2. An inductor coil of inductance L is cut into two equal parts and both the parts are connected in parallel. The net inductance is:

L/4

L/2

Question 2 of 15

3. Frequency of infrared wave is approximately:

10¹⁶Hz

10¹⁴Hz

10⁹Hz

10¹⁸ Hz

Question 3 of 15

4. The coefficient of mutual inductance. When magnetic flux changes by 2 x 10⁻² Wb and current changes by 0.01 A is

3 Henry

2 Henry

4 Henry

8 Henry

Question 4 of 15

5. In an ideal parallel LC circuit, the capacitor is charged by connecting it to a D.C. source which is then disconnected. The current in the circuit

Becomes zero instantaneously

Grows monotonically

Decays monotonically

Oscillates instantaneously

Question 5 of 15

6. In an AC circuit the potential differences across an inductance and resistance joined in series are respectively 16 V and 20 V. The total potential difference of the source is:

53.5 V

20.0 V

31.9 V

25.6 V

Question 6 of 15

7. An A.C. circuit containing only capacitance, the current:

Remains in phase with voltage

Leads the voltage by 90°

Leads the voltage in 180°

Legs the voltage by 90°

Question 7 of 15

8. A 50 Hz a.c. source of 20 volt is connected across R and C as shown in figurer. The voltage across R is 12 volt. The voltage across C is:

8 V

10 V

16 V

Not possible to determine unless values of R and C are given

Question 8 of 15

9. With the decreases of current in the primary coil from 2 amperes to zero value in 0.01s the emf generated in the secondary coil is 1000 volts. The mutual inductance of the two coils is

5.00 H

1.25 H

2.50 H

10.00 H

Question 9 of 15

10. The current gain for a transistor working as common base amplifier is 0.96. If the emitter current is 7.2 mA, the base current will be:

0.42 mA

0.29 mA

0.49 mA

0.35 mA

Question 10 of 15

11. Turn ratio in a step up transformer is 1 : 2 if a Lechlanche cell of 1.5 V is connected across the input, then the voltage across the output will be

Zero

0.75 V

0.1 V

1.5 V

Question 11 of 15

12. Which wavelength of sun is used finally as electric energy?

Infra red waves

Radio waves

Micro waves

Visible light

Question 12 of 15

13. The pressure exerted by an electromagnetic wave of intensity 1 (watt/m²) on a non-reflecting surface is: [c is the velocity of light]

Ic²

I/c

I/c²

Question 13 of 15

14. An AC source of angular frequency ω is fed across a resistor R and a capacitor C in series. The current registered is I. If now the frequency of source is changed to ω/3 (but maintaining the same voltage), the current in the circuit is found to be halved. Calculate the ratio of reactance to resistance at the original frequency ω

√4/5

√2/5

√3/5

√1/5

Question 14 of 15

15. In a circuit, the current lags behind the voltage by a phase difference of π/2, the circuit will contain which of the following:

Only C

R and C

Only L

Only R

Question 15 of 15

Test Name	Alternating Current & Electromagnetic Waves Test
Subject	Physics
Test Type	MCQs
Total Question	15
Total Marks	30
Total Time	15 Mints
Test Help For	Physics Subject Test Prep. All Admissions Test. All Jobs Test prep. Medical Test prep. Engineering Test prep.

Test By Subject	Physics
Test By Topics	Physics Subject

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