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# NCERT Solutions for Class 12 Physics Chapter 8 – Electromagnetic Waves - PDF Download

The NCERT Solutions for Class 12 Physics Chapter 8 Electromagnetic Waves provide detailed answers to the textbook numerical problems, theory questions and exercises. In Class 12 Physics, there are many tough formulas and equations. If you want to score well in your board exams, it is important to solve the exercise questions provided at the end of each chapter using the NCERT Solutions for Class 12 Physics.

Most frequently, questions that are asked in Class 12 Physics board exams are directly taken from the NCERT textbook. Electromagnetism is one of the important topics in the board exam. Therefore, you are suggested to refer to the NCERT Solutions for Class 12 Physics to attain a firm grip on the chapter as well as the subject.

## Concepts Covered in Class 12 Physics Chapter 8 Electromagnetic Waves

There are a total 4 topics in this chapter which we will discuss in-depth.

1. Introduction

2. Displacement Current

3. Electromagnetic Waves

• Sources of electromagnetic waves
•  Nature of electromagnetic waves
1. Electromagnetic Spectrum

• Microwaves

• Infrared waves

• Visible rays

• Ultraviolet rays

• X-rays

• Gamma rays

### Introduction

In chapter 8 Electromagnetic Waves, we first discuss the need for displacement current and its consequences. The broad spectrum of electromagnetic waves, stretching from gamma rays (wavelength ~10–12 m) to long radio waves (wavelength ~106 m) is described.

### Displacement Current

The displacement current is known as the current which comes into play in the region in which the electric field and the electric flux are changing with period of time.

### Electromagnetic Waves

EM waves or Electromagnetic waves are waves that are created as a result of vibrations between an electric field and a magnetic field.

Examples of electromagnetic waves include microwaves,radio waves, infrared, visible light, ultraviolet, x-rays, and gamma rays.

#### Sources of Electromagnetic Waves

There are a total 7 sources of EM waves or Electromagnetic Waves : Radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

#### Nature of Electromagnetic Waves

The electromagnetic wave or EM wave has a transverse in nature. Electric field and magnetic field vectors in an electromagnetic wave are perpendicular to each other and also perpendicular to the wave's propagation direction. This type of electromagnetic wave nature is known as transverse nature.

### Electromagnetic Spectrum

The electromagnetic spectrum range covers electromagnetic waves with frequencies from below one hertz to above 1025 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus.

Radio waves are having the longest wavelength in the electromagnetic spectrum. These waves are a kind of electromagnetic radiation and have a frequency range from high 300 GHz to low as 3 kHz, though somewhere it is defined above 3 GHz as microwaves.

We use radio waves for communications. This radio tower has two kind of antennas rectangular and circular antennas to transmit and receive radio frequency.

#### Microwaves

The microwaves are the electromagnetic waves which have frequencies in the range 300 MHz to 300GHz. Microwaves can heat an object on which they are incident. Such property is used in electrical appliances such as a microwave oven.

#### Infrared Waves

Infrared light, or infrared waves, are part of the electromagnetic spectrum. We encounter Infrared waves every day; the human eye cannot see it, but humans can detect it as heat. A remote control uses light waves to change channels on your TV.

#### Visible Rays

The visible light spectrum is another segment of the electromagnetic spectrum that the human eye can view. The 3 uses of visible lights are in photography, electronic gadgets and fiber optic communications. The range of light that people can easily recognize with their natural eyes is known as visible light.

#### Ultraviolet Rays

Ultraviolet (UV) radiation is a form of non-ionizing radiation that is emitted by the artificial sources sun.While it has some benefits for human beings, including the creation of Vitamin D, it also can cause health risks.

#### X-Rays

X-rays are a form of electromagnetic radiation, likewise visible light. Unlike light, x-rays have higher energy and can pass through our body and most objects.In Medical field we use x-rays to generate images of tissues and structures inside the body.

#### Gamma Rays

Gamma rays have the smallest wavelengths in the electromagnetic spectrum and the most energy of any wave in the spectrum. They are produced by the hottest and most energetic objects in the universe, for instance neutron stars and pulsars, supernova explosions, and regions around black holes.

## Benefits of NCERT Solutions for Class 12 Physics

NCERT Solutions are very beneficial, especially in the board exams if you want to score well in your exams. Following are many benefits of NCERT Solutions Class 12 Physics, such as

• Solving NCERT questions also gives an idea about the pattern of questions.

• NCERT Solutions are explained in detail with understandable language.

• These Solutions are specified as marks-oriented maths important questions simultaneously.

Question 1 : What are the topics in chapter 8 NCERT Physics?

Answer : Following are the topics in chapter 8

1. Introduction

2. Displacement Current

3. Electromagnetic Waves

• Sources of electromagnetic waves

• Nature of electromagnetic waves

4. Electromagnetic Spectrum

• Microwaves

• Infrared waves

• Visible rays

• Ultraviolet rays

• X-rays

• Gamma rays

Question 2 : What is Radio Waves?

Answer: Radio waves are having the longest wavelength in the electromagnetic spectrum. These waves are a kind of electromagnetic radiation and have a frequency range from high 300 GHz to low as 3 kHz, though somewhere it is defined above 3 GHz as microwaves.