Alternating Current Electromagnetic Waves Test Online

1. In a circuit the coil of a choke:

2. 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:

3. In the circuit shown below what will be the reading of the voltmeter and ammeter? (Total impedance of circuit Z = 100

Ω)

4. According to Maxwell’s hypothesis, changing of electric field give rise to:

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

6. 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

7. 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:

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

9. 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:

10. 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

11. An inductor and a resistor in series are connected to an A.C. supply of variable frequency. As the frequency of the source is increased, the phase angle between current and the potential difference across L with:  

12. A coke coil has:

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

14. If an AC main supply is given to be 220 v. The average emf during a positive half cycle will be

15. If we decrease the frequency of the applied A.C. with a purely capacitive load, do (1) the amplitude of V_c and (2) amplitude of I_c increase, decrease of remain the same.