## In an ideal transformer, the voltage and the current in the primary coil are 200V and 2A, respectively…..

Q: In an ideal transformer, the voltage and the current in the primary coil are 200V and 2A, respectively. If the voltage in the secondary coil is 200V, then the value of current in the secondary coil will be

(a) 0.2A

(b) 2A

(c) 10A

(d) 20A

Ans: (a)

## The power factor of the circuit in figure is1/√2 . The capacitance of the circuit is equal to

Q: The power factor of the circuit in figure is 1/√2 . The capacitance of the circuit is equal to

(a) 400 μF

(b) 300 μF

(c) 500 μF

(d) 200 μF

Ans: (c)

## Current in an ac circuit is given by I = 3 sinωt + 4 cosωt, then….

Q: Current in an ac circuit is given by I = 3 sinωt + 4 cosωt, then

(a) rms value of current is 5A.

(b) mean value of this current in any one half period will be 6/π.

(c) if voltage applied is V = Vm sin ωt, then the circuit may be containing resistance and capacitance only.

(d) if voltage applied is V = Vm sin ωt, the circuit may contain resistance and inductance only.

Ans: (c)

## A 50W, 100V lamp is to be connected to an ac mains of 200V, 50 Hz. What capacitor….

Q: A 50W, 100V lamp is to be connected to an ac mains of 200V, 50 Hz. What capacitor is essential to be put in series with the lamp?

(a) $\displaystyle \frac{25}{\sqrt2}$ μF

(b) $\displaystyle \frac{50}{\pi \sqrt3}$ μF

(c) $\displaystyle \frac{50}{\sqrt2}$ μF

(d) $\displaystyle \frac{10}{\pi \sqrt3}$ μF

Ans: (b)

## Two alternating voltage generators produce emfs of the same amplitude E0 but with a phase difference….

Q: Two alternating voltage generators produce emfs of the same amplitude E0 but with a phase difference of π/3. The resultant emf is

(a) E0 sin[ωt + (π/3)]

(b) E0 sin[ωt+ (π/6)]

(c) E0 sin[ωt + (π/6)]

(d) E0 sin[ωt + (π/2)]

Ans: (c)