Electromagnetic Light
The properties of light as an electromagnetic wave.
Light is a transverse electromagnetic wave consisting of oscillating electric and magnetic fields. It exhibits wave-particle duality.
This unit covers the electromagnetic spectrum, the universal speed of light constant, wave polarization filters, and the quantum particle nature of photons.
Key Takeaways
- •Light travels at a constant speed c ≈ 3.0 × 10⁸ m/s in a vacuum.
- •The electromagnetic spectrum ranges from long radio waves to short gamma rays.
- •Polarization isolates light oscillations to a single plane.
Core Concepts & Definitions
1Wave-Particle Duality
Light behaves as a continuous wave when propagating (diffraction, interference) and as quantized packets of energy called photons when interacting with matter (photoelectric effect).
•Photon energy: E = h * f, where h is Planck's constant.
•Wavelength is inversely proportional to photon energy.
2The Electromagnetic Spectrum
The continuum of all electromagnetic wave frequencies.
•Visible light represents a tiny band between 400 nm (violet) and 700 nm (red).
•Shorter wavelengths (UV, X-rays, Gamma) carry higher energy and are ionizing.
Quick Revision Notes
- •The speed of light in a vacuum (c) is a universal speed limit.
- •Higher frequency means higher energy but shorter wavelength.