Electromagnetic Waves – Class 12 | Chapter – 8 | Physics Short Notes Series PDF for NEET & JEE

Electromagnetic WavesElectromagnetic waves are a type of wave that consists of oscillating electric and magnetic fields, and which can travel through a vacuum or a medium. These waves are generated by the movement of charged particles, such as electrons.

Electromagnetic waves include a wide range of frequencies, which are organized into a spectrum that includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. The frequency of the wave determines its energy and properties. For example, higher frequency waves such as X-rays and gamma rays are more energetic and can cause ionization, while lower frequency waves like radio waves and microwaves are used for communication and heating.

Equation of Electromagnetic Waves

The equation of electromagnetic waves is described by Maxwell’s equations, which are a set of four partial differential equations that relate the electric and magnetic fields to their sources, such as charges and currents.

One of the most important equations in this set is the wave equation, which describes the propagation of electromagnetic waves through space. In free space, without any sources of charge or current, the wave equation takes the form:

2E = με(∂2E/∂t2)

where ∇2 is the Laplacian operator, E is the electric field, t is time, μ is the permeability of free space, and ε is the permittivity of free space.

This equation shows that the electric field E satisfies a second-order partial differential equation, with a wave-like solution propagating through space with a velocity equal to the speed of light c = 1/√(με). This wave solution has the form:

E(x,t) = E0 sin(kx – ωt)

where E0 is the amplitude of the electric field, k is the wave number (k = 2π/λ, where λ is the wavelength), and ω is the angular frequency (ω = 2πf, where f is the frequency).

The equation of electromagnetic waves shows that they are transverse waves, meaning that the electric and magnetic fields are perpendicular to each other and to the direction of propagation.

Applications of Electromagnetic Waves

Electromagnetic waves have a wide range of applications in modern technology, science, and daily life. Here are some of the most common applications of electromagnetic waves:

  • Communication: Electromagnetic waves are used for communication purposes, such as radio waves for broadcasting, television, and mobile phones. Microwaves are also used for wireless communication, including Wi-Fi, Bluetooth, and satellite communication.
  • Medical Diagnosis and Treatment: Electromagnetic waves are used in medical imaging, such as X-rays, CT scans, and MRI. They are also used for therapeutic purposes, such as in radiation therapy for cancer treatment.
  • Remote Sensing: Electromagnetic waves are used for remote sensing applications, such as in weather forecasting, radar systems, and satellite imaging. They are also used to monitor the earth’s atmosphere, oceans, and land surfaces.
  • Energy Production: Electromagnetic waves are used in the production of electricity, such as in solar panels and wind turbines.
  • Lighting: Electromagnetic waves in the visible spectrum are used for lighting purposes, such as in incandescent bulbs, fluorescent lights, and LED lights.
  • Materials Processing: Electromagnetic waves are used for materials processing, such as in microwave ovens and industrial heating.
  • Astronomy: Electromagnetic waves are used in astronomy to study the properties of celestial objects and to detect cosmic radiation.

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By Team Learning Mantras

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