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

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Chapter 7 Related Articles
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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.
A 500 nm photon is incident normally on a perfectly reflecting surface and is reflected. The value of momentum transferred to the surface is:
- \( 3.87 \times 10^{-43} \, \text{kg} \, \text{ms}^{-1} \)
- \( 2.5 \times 10^{-30} \, \text{kg} \, \text{ms}^{-1} \)
- \( 2.65 \times 10^{-27} \, \text{kg} \, \text{ms}^{-1} \)
- \( 1.33 \times 10^{-27} \, \text{kg} \, \text{ms}^{-1} \)
View Solution
2.
The magnetic field in a plane electromagnetic wave travelling in glass (\( n = 1.5 \)) is given by \[ B_y = (2 \times 10^{-7} \text{ T}) \sin(\alpha x + 1.5 \times 10^{11} t) \] where \( x \) is in metres and \( t \) is in seconds. The value of \( \alpha \) is:
- \( 0.5 \times 10^3 \, \text{m}^{-1} \)
- \( 6.0 \times 10^2 \, \text{m}^{-1} \)
- \( 7.5 \times 10^2 \, \text{m}^{-1} \)
- \( 1.5 \times 10^3 \, \text{m}^{-1} \)
View Solution
3.
The radius of a nucleus of mass number 125 is:
- 6.0 fm
- 30 fm
- 72 fm
- 150 fm
View Solution
4.
Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))
View Solution
5.
If Bohr’s quantization postulate (angular momentum \( = \frac{nh}{2\pi} \)) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun? Explain.
View Solution
6.
A part of a wire carrying \( 2.0 \, \text{A} \) current and bent at \( 90^\circ \) at two points is placed in a region of uniform magnetic field \( \vec{B} = -0.50 \, \hat{k} \, \text{T} \), as shown in the figure. Calculate the magnitude of the net force acting on the wire.
View Solution

View All

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NCERT Solutions For Class 12 Physics Chapter 7: Alternating Current

NCERT Solutions for Class 12 Physics Chapter 7

Previous Year Questions

Class 12 Physics Chapter 7 Topics Covered

CBSE CLASS XII Related Questions

1.
A 500 nm photon is incident normally on a perfectly reflecting surface and is reflected. The value of momentum transferred to the surface is:

2.
The magnetic field in a plane electromagnetic wave travelling in glass (\( n = 1.5 \)) is given by \[ B_y = (2 \times 10^{-7} \text{ T}) \sin(\alpha x + 1.5 \times 10^{11} t) \] where \( x \) is in metres and \( t \) is in seconds. The value of \( \alpha \) is:

3.
The radius of a nucleus of mass number 125 is:

4.
Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

5.
If Bohr’s quantization postulate (angular momentum \( = \frac{nh}{2\pi} \)) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun? Explain.

6.
A part of a wire carrying \( 2.0 \, \text{A} \) current and bent at \( 90^\circ \) at two points is placed in a region of uniform magnetic field \( \vec{B} = -0.50 \, \hat{k} \, \text{T} \), as shown in the figure. Calculate the magnitude of the net force acting on the wire.

Similar Physics Concepts

Comments

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NCERT Solutions For Class 12 Physics Chapter 7: Alternating Current

NCERT Solutions for Class 12 Physics Chapter 7

Previous Year Questions

Class 12 Physics Chapter 7 Topics Covered

CBSE CLASS XII Related Questions

1.A 500 nm photon is incident normally on a perfectly reflecting surface and is reflected. The value of momentum transferred to the surface is:

2.The magnetic field in a plane electromagnetic wave travelling in glass (\( n = 1.5 \)) is given by \[ B_y = (2 \times 10^{-7} \text{ T}) \sin(\alpha x + 1.5 \times 10^{11} t) \] where \( x \) is in metres and \( t \) is in seconds. The value of \( \alpha \) is:

3.The radius of a nucleus of mass number 125 is:

4.Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

5. If Bohr’s quantization postulate (angular momentum \( = \frac{nh}{2\pi} \)) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun? Explain.

6. A part of a wire carrying \( 2.0 \, \text{A} \) current and bent at \( 90^\circ \) at two points is placed in a region of uniform magnetic field \( \vec{B} = -0.50 \, \hat{k} \, \text{T} \), as shown in the figure. Calculate the magnitude of the net force acting on the wire.

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

1.
A 500 nm photon is incident normally on a perfectly reflecting surface and is reflected. The value of momentum transferred to the surface is:

2.
The magnetic field in a plane electromagnetic wave travelling in glass (\( n = 1.5 \)) is given by \[ B_y = (2 \times 10^{-7} \text{ T}) \sin(\alpha x + 1.5 \times 10^{11} t) \] where \( x \) is in metres and \( t \) is in seconds. The value of \( \alpha \) is:

3.
The radius of a nucleus of mass number 125 is:

4.
Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

5.
If Bohr’s quantization postulate (angular momentum \( = \frac{nh}{2\pi} \)) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun? Explain.

6.
A part of a wire carrying \( 2.0 \, \text{A} \) current and bent at \( 90^\circ \) at two points is placed in a region of uniform magnetic field \( \vec{B} = -0.50 \, \hat{k} \, \text{T} \), as shown in the figure. Calculate the magnitude of the net force acting on the wire.