## An AC voltage source described by V = 10 cos (π/2)t is connected to a 1μF capacitor as shown ….

Q: An AC voltage source described by V = 10 cos (π/2)t is connected to a 1μF capacitor as shown in figure. The key K is closed at t = 0 s. The time (t > 0) after which the magnitude of current I reaches its maximum value for the first time is

(a) 1s

(b) 2s

(c) 3s

(d) 4s

Ans: (a)

## In the circuit shown in figure, the power consumed is ….

Q: In the circuit shown in figure, the power consumed is

(a) zero

(b) $\displaystyle \frac{V_0^2}{2 R}$

(c) $\displaystyle \frac{V_0^2 R}{2(R^2 + \omega^2 L^2) }$

(d) None of these

Ans: (c)

## A circuit contains resistance R and an inductance L in series. An alternating voltage V ….

Q: A circuit contains resistance R and an inductance L in series. An alternating voltage V = V0 sin ωt is applied across it. The currents in R and L respectively will be

(a)IR = I0 cos ωt , IL = I0 cos ωt

(b) IR = -I0 sin ωt , IL = I0 cos ωt

(c) IR = I0 sin ωt , IL = -I0 cos ωt

(d) None of the above

Ans: (d)

## A capacitor and resistor are connected with an AC source as shown in figure. Reactance of capacitor…

Q: A capacitor and resistor are connected with an AC source as shown in figure. Reactance of capacitor is XC = 3Ω and resistance of resistor is 4Ω . Phase difference between current I and I1 is [ tan-1 (3/4)= 37° ]

(a) 90°

(b) zero

(c) 53°

(d) 37°

Ans: (c)

## An AC voltage source V = Vo sin ωt is connected across resistance R and capacitance C as shown….

Q: An AC voltage source V = V0 sin ωt is connected across resistance R and capacitance C as shown in figure. It is given that R = 1/ωC . The peak current is I0 . If the angular frequency of the voltage source is changed to ω /√3 , then the new peak current in the circuit is

(a) I0 /2

(b) I0 /√2

(c) I0 /√3

(d) I0 /3

Ans: (b)