NCERT Solutions For Class 12 Physics Chapter 7: Alternating Current

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NCERT Solutions for Class 12 Physics Chapter 7 Alternating Current (AC) are provided in this article. Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to Direct Current (DC) which flows only in one direction. AC voltage is preferable in the circuits because it can be easily and efficiently converted into another voltage using a transformer.

Unit 4 Electromagnetic Induction and Alternating Currents along with Unit 3 Magnetic Effects of Current and Magnetism has a weightage of 17 marks in the CBSE Board examinations. The NCERT Solutions for Class 12 Physics Chapter 7 deals with concepts of alternating current, LC Oscillations, AC voltage applied to an inductor, capacitor, Power in Alternating Current, etc.

Download PDF: NCERT Solutions for Class 12 Physics Chapter 7

NCERT Solutions for Class 12 Physics Chapter 7

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Class 12 Physics Chapter 7 Topics Covered

Alternating Current refers to a changing voltage electric supply. It can be efficiently transformed from one form to another.
The charge and the electric current in a charged capacitor undergo LC Oscillations when it is connected to an inductor in the circuit.
RMS refers to the Root Mean Square of instantaneous current values. RMS value of alternating current is given by the direct current that flows through a resistance.

$I_{rms} = \frac{I_0}{\sqrt{2}} = 0.707 I_0 $

Wattless Current is when the average power consumed in an AC circuit corresponds to Zero.

The average power dissipated in AC circuit is given by:

P = VI cos ϕ

Here, V is the voltage applied, I is the current flowing, and ϕ is the phase difference between voltage and current

Power factor is a factor through which the apparent power should be multiplied in order to get active power.

cos θ = P/\|S\| = Actual power/Apparent power

Also Read:

Chapter 7 Related Articles
AC Generator	AC Voltage applied to an Inductor	AC Voltage Applied to a Capacitor
AC Voltage applied to LCR Circuit	AC Voltage applied to Resistor	Power in AC Circuit
Capacitive reactance formula	Difference between AC and DC Motor	Phasor Representation AC

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CBSE CLASS XII Related Questions

1.
Consider a cylindrical conductor of length $l$ and area of cross-section $A$. Current $I$ is maintained in the conductor and electrons drift with velocity $\vec{v}_d$ ($|\vec{v}_d| = \frac{e|\vec{E}|}{m}\tau$), (where symbols have their usual meanings). Show that the conductivity $\sigma$ of the material of the conductor is given by
$$\sigma = \frac{ne^2}{m}\tau.$$
View Solution
2.
The resistance of a metal wire at $20^\circ\text{C}$ is $1.05\,\Omega$ and at $100^\circ\text{C}$ is $1.38\,\Omega$. Determine the temperature coefficient of resistivity of this metal.
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3.
Determine the current in the $ 3 \, \Omega $ branch of a Wheatstone Bridge in the circuit shown in the figure.
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4.
Consider a cylindrical conductor of length $l$ and area of cross-section $A$. Current $I$ is maintained in the conductor and electrons drift with velocity $\vec{v}_d$ ($|\vec{v}_d| = \frac{e|\vec{E}|}{m}\tau$), (where symbols have their usual meanings). Show that the conductivity $\sigma$ of the material of the conductor is given by
$$\sigma = \frac{ne^2}{m}\tau.$$
View Solution
5.
Consider the nuclear reaction $ X \to Y + Z $. Let $ M_x $, $ M_y $, and $ M_z $ be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?
- $ (M_x - M_z)<M_y $
- $ (M_x - M_y)<M_z $
- $ M_x>(M_y + M_z) $
- $ M_x<(M_y + M_z) $
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6.
The resistance of a metal wire at $20^\circ\text{C}$ is $1.05\,\Omega$ and at $100^\circ\text{C}$ is $1.38\,\Omega$. Determine the temperature coefficient of resistivity of this metal.
View Solution