Optics - Physics Concepts

Introduction to Optics

Optics is the branch of physics that studies the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it.

Key Concepts

Reflection

The bouncing back of light when it hits a surface.

Refraction

Bending of light as it passes through different media.

$Refraction$

Diffraction

Spreading of light when it passes through a narrow slit.

$Diffraction$

Interference

When two waves overlap to form a resultant wave.

Important Equations

v = fλ

Wave Speed Equation

n = c / v

Refractive Index

1/f = 1/v - 1/u

Lens Formula

θ = λ/d

Diffraction Angle

Applications of Optics

Microscopes and Telescopes: Use lenses and mirrors to magnify distant or small objects.
Fiber Optics: Transmit light signals over long distances for communication.
Laser Technology: Used in surgery, communication, and cutting materials.
Spectroscopy: Used in chemical analysis and astronomy.

Example Problems

1. A light ray passes from air (n=1.0) to water (n=1.33). If the angle of incidence is 30°, find the angle of refraction.

Solution: Use Snell’s Law: n₁sinθ₁ = n₂sinθ₂ ⇒ 1×sin30° = 1.33×sinθ₂ ⇒ θ₂ ≈ 22°

2. A convex lens has a focal length of 10 cm. An object is placed 15 cm from the lens. Find the image distance.

Solution: 1/f = 1/v - 1/u ⇒ 1/10 = 1/v - 1/(-15) ⇒ v ≈ 30 cm

3. What is the diffraction angle for light of wavelength 600 nm passing through a slit of width 0.1 mm?

Solution: θ = λ/d = 600×10⁻⁹ / 0.1×10⁻³ = 0.006 rad ≈ 0.34°