alternating-currentWHERE cd.courseId=3 AND cd.subId=8 AND chapterSlug='alternating-current' and status=1SELECT ex_no,page_number,question,question_no,id,chapter,solution FROM question_mgmt as q WHERE courseId='3' AND subId='8' AND chapterId='121' AND ex_no!=0 AND status=1 ORDER BY ex_no,CAST(question_no AS UNSIGNED) CBSE Class 12 Free NCERT Book Solution for Physics

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Chapter 7 : Alternating Current


The seventh chapter of NCERT class 12 Physics has only nine topics in all. You get detailed knowledge and understanding about alternating currents and its application in resistor, LCR series circuit, peak and RMS value of alternating voltage, reactance, impedance, LC oscillations, resonance and power in AC circuits, AC generator and transformer, watt-less current, etc. At the end of the chapter, you will find exercises for you to solve.

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


Exercise 1
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:


Exercise 1
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.