NCERT Solutions For Class 12 Physics Chapter 8: Electromagnetic Waves

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NCERT Solutions for Class 12 Physics Chapter 8 Electromagnetic Waves are provided in this article. The waves that are produced when an electric field comes into contact with a magnetic field are known as Electromagnetic Waves or EM waves. The concept of EM waves can also be understood by visualizing the waves in which there are sinusoidal variations of vectors of the magnetic and electric field which are perpendicular to each other and also at right angles to the wave propagation direction.

Unit 5 - Electromagnetic Waves along with Unit 6 - Optics has a weightage of 18 marks in the CBSE Class 12 Physics Examination. The NCERT Solutions for Class 12 Physics Chapter 8 covers concepts of displacement current, electromagnetic spectrum, Maxwell Equations, etc.

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NCERT Solutions for Class 12 Physics Chapter 8

The NCERT solutions for class 12 physics chapter 8: Electromagnetic waves are given below:

CBSE Class 12 Physics Chapter 8 Important Topics

Electromagnetic Waves are the waves produced when an electric field comes in contact with a magnetic field.

The direction of the propagation of EM waves is given by a vector cross product of the electric and magnetic fields as

$\overrightarrow E \times \overrightarrow B$

Equation of Speed of EM Wave: The relation between the speed of light, permittivity constant, and permeability constant is as follows:

$c = {1 \over \mu_0 \epsilon_0}$

The wavelength for the various spectrum of light is as follows -
- Radio Waves > 0.1 m
- Microwave - 0.1m to 1 mm
- Infrared waves - 1 mm to 700 nm
- Visible light - 700 nm to 400 nm
- Ultraviolet - 400 nm to 1nm
- X-rays - 1nm to 10^-3 nm
- Gamma rays < 10^-3 nm

According to their wavelength or frequency, EM waves can be classified as Electromagnetic Spectrum that ranges from 400 nm to 700 nm.

Applications of Electromagnetic Waves: Electromagnetic Waves play an important role in communication technology.

The infrared radiations are used in the security cameras for night vision. UV rays can be helped to detect forged banknotes.

Also Read:

Chapter 8 Related Articles
Electromagnetic Radiations	Electromagnetic Pulse	Wave Nature of Electromagnetic Radiation
Electromagnetism	Wavelength formula	Electromagnetic Field
Faraday’s Laws of Induction	Electromagnetic Induction	Electromagnetic Spectrum
X-Rays	Radio waves	Infrared radiation
Gamma radiation	Types of radiation	Impedance of free space

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CBSE CLASS XII Related Questions

1.
Two copper wires having their radii in the ratio of 3 : 2 are connected in series across a battery. Find the ratio of the drift velocities of the electrons in the wires.

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2.
Read the following paragraph and answer the questions that follow.
In an experiment with convex lens of focal length f, the screen is fixed at a distance D from the object. A student slowly moves the lens away from the object towards the screen and finds that she is able to form sharp image of the object for two positions of the lens. The distance between these two positions of the lens is d.

3.
An electric field $\vec{E}$ is established across the ends of a cylindrical conductor of length L and area of cross-section A. Discuss how electrons attain an average velocity, independent of time. Hence, obtain a relation between current in the conductor and this ‘average velocity’ of electrons.

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4.
A charged particle $+q$ in an electric field $\vec{E}$ experiences a force in the direction of the electric field. As a result, its kinetic energy changes. Similarly, the charged particle also experiences a force when it moves in a magnetic field $\vec{B}$. But this magnetic force is perpendicular to both velocity $\vec{v}$ of the charged particle and the magnetic field $\vec{B}$, so it cannot change the kinetic energy of the charged particle. Consider two charged particles 1 and 2 of masses $m$ and $\frac{m}{2}$ having charges $-q$ and $+2q$ respectively. They are accelerated from rest through the same potential difference $V$ and acquire kinetic energy $K_1$ and $K_2$. Then they enter in a region of uniform magnetic field $\vec{B}$ perpendicular to their velocities.

5.
Capacitors are manufactured with certain standard capacitances and working voltages. However, these standard values may not be the ones that are actually needed in a particular application. Two or more capacitors can be grouped in series or in parallel to achieve desired capacitance and voltage. When connected in series, the total capacitance decreases while the voltage rating increases, whereas in parallel connections, the total capacitance increases and maintains the same voltage rating. A capacitor stores energy in the electric field between its plates and stored energy is proportional to the square of the voltage and capacitance $U = \frac{1}{2}CV^2$, where symbols have their usual meanings.
Two capacitors, one of $3 \ \mu$F and the other of $6 \ \mu$F, are connected in series in the circuit as shown in the figure, for a long time. }

6.
This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?

View Solution

NCERT Solutions For Class 12 Physics Chapter 8: Electromagnetic Waves

NCERT Solutions for Class 12 Physics Chapter 8

CBSE Class 12 Physics Chapter 8 Important Topics

CBSE CLASS XII Related Questions

1.
Two copper wires having their radii in the ratio of 3 : 2 are connected in series across a battery. Find the ratio of the drift velocities of the electrons in the wires.

6.
This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?

Similar Physics Concepts

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NCERT Solutions For Class 12 Physics Chapter 8: Electromagnetic Waves

NCERT Solutions for Class 12 Physics Chapter 8

CBSE Class 12 Physics Chapter 8 Important Topics

CBSE CLASS XII Related Questions

1.Two copper wires having their radii in the ratio of 3 : 2 are connected in series across a battery. Find the ratio of the drift velocities of the electrons in the wires.

6.This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

1.
Two copper wires having their radii in the ratio of 3 : 2 are connected in series across a battery. Find the ratio of the drift velocities of the electrons in the wires.

6.
This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?