Match List – I with List – II: List – I List – II (A) UV rays (i) Diagnostic tool in medicine (B) X-rays(ii) Water purification (C) Microwave(iii) Communication, Radar (D) Infrared wave(iv) Improving visibility in foggy daya Choose the correct answer from the options given below:

(A)-(ii), (B)-(i), (C)-(iii), (d)-(iv)

(A)-(iii), (B)-(ii), (C)-(i), (D)-(iv)

(A)-(ii), (B)-(iv), (C)-(iii), (D)-(i)

(A)-(iii), (B)-(i),(C)-(ii), (D)-(iv)

Physics Electromagnetic Waves: Overview, Questions, Preparation

Updated on Sep 17, 2025 14:37 IST

Electromagnetic waves are waves comprising of electric and magnetic waves that can travel through vacuum and do not require a medium to propagate. These waves travel in space at the speed of light (c=3 * 10^8 m/s). The electric and magnetic fields are perpendicular to each other i.e. they oscillate at an angle of 90 degree in the direction where waves propagate. This topic is one of the most important aspects of the chapter “electromagnetism” understanding the core fundamentals of this topic can help candidates solve a wide range of numerical problems that are frequently asked in JEE MAINS.

Table of content

Structure and Key Characteristics
Types of Electromagnetic Waves
Mathematical Expressions
Real-World Applications
Physics Class 12 NCERT Solutions

Structure and Key Characteristics

The electromagnetic waves are transverse waves. Let us briefly understand the meaning of this. An electromagnetic wave comprises of 2 fields:

Electric Field (𝐄)
Magnetic Field (𝐁)

Both of these fields are arranged in such a way that they lie perpendicular to each other and form an angle of 90 degree. The magnetic field oscillates perpendicularly to the direction of electric field and the waves carry energy while moving forward in the direction of wave propagation.

Note: These waves move at the speed of light i.e. 3 * 10^8 m/s.

Types of Electromagnetic Waves

Here are some of the major categories of waves recognized in the EM spectrum according to their frequency or wavelength:

Radio Waves
Microwaves
Infrared Rays
UV Rays
X-Rays
Visible Light
Gamma Rays

Mathematical Expressions

A wave moving in free space can be denoted by the equations:

E=E0sin(kx−ωt) [for electric field]

B=B0sin(kx−ωt) [for magnetic field]

Where,

E0, B0: amplitudes of the electric and magnetic fields

ω=2πf (angular frequency)

k=2π/ λ (wave number)

x: position

t: time

Also, A wave moving in vacuum is denoted by:

B0=E0/c
Where, c = 3 * 10^8 m/s

Real-World Applications

These electromagnetic waves are used in a wide range of electronic devices that are an integral part of our day-to-day lives. Some of these are mentioned as below:

Radio
TVs
Bluetooth and Wifi
Microwaves
Mobile Phones
Spectroscopy
Solar panels
X-Rays and MRI scans
Satellites
IoT sensors
GPS technologies

Physics Electromagnetic Waves

Try these practice questions

Q1:

A plane electromagnetic wave travels in a medium of relative permeability 1.61 and relative permittivity 6.44. If magnitude of magnetic intensity is 4.5 × 10^-2 Am^-1 at a point, what will be the approximate magnitude of electric field intensity at tha

View Full Question

16.96 Vm^-1

Q2:

An EM wave propagating in x-direction has wavelength of 8 mm. The electric field vibrating y-direction has maximum magnitude of 60 Vm^-1. Choose the correct equations for electric and magnetic fields if the EM wave is propagating in vacuum:

$E_{y} = 60 s i n [\frac{π}{4} \times 1 0^{3} (x - 3 \times 1 0^{8} t)] \hat{j} V m^{- 1}$

$B_{z} = 2 s i n [\frac{π}{4} \times 1 0^{3} (x - 3 \times 1 0^{8} t)] \hat{k} T$

$E_{y} = 60 s i n [\frac{π}{4} \times 1 0^{3} (x - 3 \times 1 0^{8} t)] \hat{j} V m^{- 1}$

$B_{z} = 2 \times 1 0^{- 7} s i n [\frac{π}{4} \times 1 0^{3} (x - 3 \times 1 0^{8} t)] \hat{k} T$

$E_{y} = 2 \times 1 0^{- 7} s i n [\frac{π}{4} \times 1 0^{3} (x - 3 \times 1 0^{8} t)] \hat{j} V m^{- 1}$

$B_{z} = 60 s i n [\frac{π}{4} \times 1 0^{3} (x - 3 \times 1 0^{8} t)] \hat{k} T$

$E_{y} = 2 \times 1 0^{- 7} s i n [\frac{π}{4} \times 1 0^{4} (x - 4 \times 1 0^{8} t)] \hat{j} V m^{- 1}$

$B_{z} = 60 s i n [\frac{π}{4} \times 1 0^{4} (x - 4 \times 1 0^{8} t)] \hat{k} T$

Physics Class 12 NCERT Solutions

Sl. No	Name of Chapter
1	Electric Charges and Fields
2	Electrostatic Potential and Capacitance
3	Current Electricity
4	Moving Charges and Magnetism
5	Magnetism and Matter
6	Electromagnetic Induction
7	Alternating Current
8	Electromagnetic Waves
9	Ray Optics and Optical Instruments
10	Wave Optics
11	Dual Nature of Radiation and Matter
12	Atoms
13	Nuclei
14	Semiconductor Electronics: Materials, Devices and Simple Circuits

Commonly asked questions

How come electric and magnetic fields are able to work together?

They work through the principle of Maxwell principle. A changing magnetic field will induce electric current and changing electric field will produce magnetic field, both in oscillating directions perpendicular to each other. Both of them move in different planes, and their interaction produces electromagnetic waves.

Are electromagnetic waves harmful to the human body?

It depends on the frequency of the wave. Rays such as Gamma rays, X-Rays etc. have higher frequencies which can lead to harmful impacts if exposed to the human body. These kind of rays cannot be even produced easily unlike low frequency rays.

Why are some electromagnetic waves invisible to the naked eye?

There are different types of electromagnetic waves and each of them have different wavelengths. Human eye can only see the light rays which have a minimum wavelength of around 400-700nm. Rays which don't meet this threshold will eventually not be visible to the humans.

Physics Electromagnetic Waves Exam

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Physics Electromagnetic Waves: Overview, Questions, Preparation

Structure and Key Characteristics

Types of Electromagnetic Waves

Mathematical Expressions

Real-World Applications

Physics Electromagnetic Waves

Try these practice questions

Physics Class 12 NCERT Solutions

Commonly asked questions

Student Forum

Other Topics under this Chapter

Other Class 12th Physics Chapters

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