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Q1 A 100 Ω resistor is connected to a 220 V, 50 Hz ac supply.
(a) What is the rms value of current in the circuit?
(b) What is the net power consumed over a full cycle?Ans: 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
Q2 (a) The peak voltage of an ac supply is 300 V. What is the rms voltage?
(b) The rms value of current in an ac circuit is 10 A. What is the peak current?
Ans: (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:
Q3 A 44 mH inductor is connected to 220 V, 50 Hz ac supply. Determine the rms value of the current in the circuit.
Ans: 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.
Alternating Current Question Answers: NCERT Class 12 Physics
Welcome to the Chapter 7 - Alternating Current, Class 12 Physics - NCERT Solutions page. Here, we provide detailed question answers for Chapter 7 - Alternating Current.The page is designed to help students gain a thorough understanding of the concepts related to natural resources, their classification, and sustainable development.
Our solutions explain each answer in a simple and comprehensive way, making it easier for students to grasp key topics and excel in their exams. By going through these Alternating Current question answers, you can strengthen your foundation and improve your performance in Class 12 Physics. Whether you're revising or preparing for tests, this chapter-wise guide will serve as an invaluable resource.
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.
Download PDF - Chapter 7 Alternating Current - Class 12 Physics
Download PDF - NCERT Examplar Solutions - Chapter 7 Alternating Current - Class 12 Physics
Exercise 1
Key Features of NCERT Class 12 Physics Chapter 'Alternating Current' question answers :
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A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is 1.5 × 103 N/C and points radially inward, what is the net charge on the sphere?
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