Electromagnetic (EM) waves are self-propagating waves consisting of oscillating electric and magnetic fields, which are perpendicular to each other and the direction of propagation.
Characteristics:
1. Nature:Transverse waves. Do not require a medium; can travel through a vacuum.
2. Structure:Electric field (ε) and magnetic field (Β) are at right angles to each other. Oscillate sinusoidally.
3. Speed:In a vacuum:
Speed in a medium depends on its refractive index.
4. Wavelength ( λ) and Frequency (f):Related by
C = λ f
5. Energy:
Energy of EM waves is quantized and carried by photons.
E = ℏf,where
ℏ = 6.626×10^-34, Js
(Planks Constant)
The EM spectrum includes waves of varying frequencies and wavelengths
1. Radio Waves: Longest wavelength, used in communication.
2. Microwaves: For cooking, radar, and wireless technologies.
3. Infrared: Heat energy, used in sensors and thermal imaging.
4. Visible Light: The only EM wave visible to the human eye (400–700 nm).
5. Ultraviolet (UV): Causes fluorescence, used in sterilization and tanning.
6. X-Rays: Penetrate soft tissue, used in medical imaging.
7. Gamma Rays: Highest energy, used in cancer therapy and astrophysics.
1. Communication:
Radio waves for broadcasting. Microwaves for satellite and mobile communication.2. Medicine:
X-rays and gamma rays in imaging and cancer treatment. Infrared in physical therapy.
3. Energy:
Visible light in photosynthesis and solar panels.
4. Industry:
Microwaves in cooking. UV for water purification.
5. Research and Astronomy:
Gamma-ray bursts, black hole studies, and spectroscopy
Reflection and Refraction: Bounce off or bend in different media.
Diffraction: Spread around obstacles.
Interference: Combine constructively or destructively.
Polarization: Alignment of oscillations in a single direction.
Radiation Pressure: Exert force due to photon momentum.
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