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?
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