6.4 Radiation and wavesApril 14, 2023

Aims

• Show that light can be reflected, refracted, diffracted and produces interference effects

• Explain that we think sound is a wave• Show that light can be reflected and refracted

Light

• When light interacts with an object it can be either reflected (bounce off), transmitted (go through) or be absorbed (transfer energy)

AbsorptionRefl

ection

Transmission

I think a light ray is a stream of tiny particles emitted by a source

My experiment show that light rays can interfere. Two streams of particles could

not do this. Light is a wave.

Refle

ction

Refr

actio

n

Diff

racti

on

Inte

rfer

ence

Refraction is the change in direction of a wave due to a change in its speed.

Reflection is the change in direction of a wavefront at an interface

Diffraction is the apparent bending of waves around small obstacles and the spreading out of waves past small openings.

Interference is the addition of two or morewaves that results in a new wave pattern.

DemonstrationsDoes sound behave like a wave?

Quantum weirdness

Reproducing Young’s double slit experiment

• We are going to repeat Young’s experiment and derive a value for the wavelength of the laser light and compare with the printed value

• You first need to make your ‘double slit’

What will happen?

• Sketch what you see with no card• Sketch what you think you will see with the

card• Sketch what you actually see• Why do you think this happens?

What is the medium?