Page 1 1. Why we prefer a choke coil to a rheostat in controlling a.c. [1] 2. A bulb connected in series with solenoid is lit by an a.c. source. If a soft iron core is introduced in the solenoid, will the bulb glow brighter ? [1] 3. Sketch a graph to show the variation of inductive reactance with frquency. [1] 4. The resistance of a coil is 10 ? for direct current. When an alternating current is passed through the coil, will the opposition remains the same ? Explain. [1] 5. A person carrying anything of metal when passes through a metal detector emits a sound. On what principle does this detector work ? [2] 6. A coil having a resistance of 60 ? and inductance of 0.500 H, connected to an a.c. source of 110 volt, 50 cycles/sec. Find the rms value of current in the circuit. [2] 7. A coil has a resistance of 10 ? and inductance of 0.4 H. It is connected to an a.c. source of 6.5 V , 90/ ? Hz. Find the average power consumed in the circuit. [2] 8. Prove that the phase difference between voltage, and current in an a.c. circuit containing only capacitor is ?/2. [2] 9. The instantaneous voltage is given by E = 140 sin 300 t. What is (i) peak current (ii) rms current and (iii) frequency of the supply. When connected to 10 ? resistance. [2] 10. A pure inductor of self induction 1 H. is connected across an alternating voltage of 115 V and frequency 60 Hz. Calculate (i) inductive reactance (ii) effective current (iii) peak current (iv) average power. [2] 11. Prove that energy remains conserved when a charge oscillates in a.c. circuit. [3] 12. Draw a phasor diagram of LCR series circuit and find expression for impedance and phase difference. [3] 13. An inductor 200 mH, capacitor 500 µF, resistor 10 ? are connected in series with a 100 V , variable frequency ac source. Calculate the (i) frequency at which the power factor of the circuit is unity. (ii) current amplitue at this frquency. (iii) Q-factor. [3] ALTERNATING CURRENT T E S T - C X I I M.M. M.O. 25 ABHA DHAMIJA PHYSICS CLASSES Off.: # D.S.S. 146, Sector-7, Main Market, KARNAL Resi.: # 1282, Sector-7, KARNAL Ph.: 8950171870 T h e L e a r n i n g C e n t r eRead More

Offer running on EduRev: __Apply code STAYHOME200__ to get INR 200 off on our premium plan EduRev Infinity!