LESSON 09
The Wave Nature of Light
Light as an electromagnetic wave.
Frequency1.00×
Amplitude1.00×
Light is an electromagnetic wave — it does not need a medium. It can reflect, refract, diffract and interfere just like sound and water waves.
The electromagnetic spectrum
Visible light is a tiny slice between infrared and ultraviolet. All electromagnetic waves travel at c = 3 × 10⁸ m/s in vacuum.
Dispersion
A prism splits white light because each colour refracts by a different amount.
Diffraction & interference
Thin films (soap bubbles, oil on water) show colour because of interference between reflected light waves.
Key Formulas
Speed of light
c = f · λ
c = 3 × 10⁸ m/s
Real-life applications
- Rainbows
- Fibre-optic internet
- Anti-reflective lens coatings
Summary
- Light is an EM wave.
- c = f·λ.
- Prisms split it; films interfere it.
Check Yourself
Q1.Why does a prism split white light?
Q2.Speed of light in vacuum is approximately…