## Sunday, 28 September 2014

### ALTERNATING CURRENT MCQ 6 TO 10

6. The potential difference V across the current i flowing through an instrument in an ac circuit of frequehcy f are given by v = 5 cos ωt volts and i = 2 sin ωt amperes (where ω = 2 πf). The power dissipated in. the instrument is. [CPMT 1977, 80; ]
 Zero watt 5 watt 10 watt 2.5 watt

7. What will be the phase difference between virtual voltage and virtual current, when the current in the circuit is wattless
 900 1800 450 600

8. The inductive reactance of an inductor of 1/π henry at 50 Hz frequency is
 50/π ohm 100 ohm π/50 ohm 50 ohm

9. An ac supply gives 30 V r.m.s. which passes through a 10 Ω resistance. The power dissipated in it is
 90 √2 w 45 √2 w 90 w 45 w

10. A resistor R, an inductor L, a capacitor C and voltmeters V1, V2 and V3 are connected to an oscillator in the circuit as shown in the adjoining diagram. When the frequency of the oscillator is increased, then at resonant frequency the reading of voltmeter V3 is equal to That of voltmeter V1 Both of the voltmeters V1 and V2 That of voltmeter V2 None of these