Alternating Current Question Answers: NCERT Class 12 Physics

Exercise 1
Q:
A:

Resistance of the resistor, R = 100 Ω

Supply voltage, V = 220 V

Frequency, ν = 50 Hz

(a) The rms value of current in the circuit is given as:

I = V / R

 = 220 / 100 = 2.20 A

(b) The net power consumed over a full cycle is given as:

P = VI

= 220 × 2.2 = 484 W


Q:
A:

(a) Peak voltage of the ac supply, V0 = 300 V

Rms voltage is given as:

(b) Therms value of current is given as:

I = 10 A

Now, peak current is given as:


Q:
A:

Inductance of inductor, L = 44 mH = 44 × 10-3 H

Supply voltage, V = 220V

Frequency, ν = 50Hz

Angular frequency, \[\begin{align}\omega = 2\pi v\end{align}\]

Inductive reactance, \begin{align}X_{L}= \omega L = 2\pi vL = 2\pi\times50\times44\times10^{-3} \Omega\end{align}

Rms value of current is given as:

\begin{align}I = \frac{v}{X_{L}}\end{align}

\begin{align} = \frac{220}{2\pi\times50\times44\times 10^{-3}} =15.92A\end{align}

Hence, the rms value of current in the circuit is 15.92 A.