# 💡Physics

Applicable for A-Level, IB, DSE, AP-Level Exams

# Optics

## Diffraction

Diffraction is the way that waves spread out as they come through a narrow gap or go around obstacles. Diffraction is important for double-slit interference and superposition.

## Two-source Interference

Through two-slits, maxima and minima can be created due the the constructive and destructive interference of waves which is stemed from their path difference.

## Young's Double Slit Experiment

Young's Double Slit Experiment, which demonstrates the superposition of light waves, shows that light behaves like a wave instead of a particle.

## Diffraction Gratings

A diffraction grating contains lots of equally spaced slits very close together hence splits and diffracts light into several beams travelling in different directions. You will need to know how to derive d sin(θ) = n λ using trigonometry.

## Refraction

From a less optically dense material to a more optically dense material, waves refract towards the normal. From a more optically dense material to a less optically dense material, waves refract away from the normal. The higher a material's optical density, the higher refractive index.

## Reflection

Snell's Law allows us to find the angle of refraction and angle of incidence given the refractive index of the 2 medium.