P5f Nature of waves

P5f - Nature of wavesInterference of waves

Constructive

Destructive

Revision - Diffraction

• Diffraction is…

• Maximum diffraction happens when…

What if there are 2 gaps?

Diffraction patterns• When waves are ____________

by two slits they overlap which causes _____________

• _______________ interference cancels the waves out leaving blank spaces

• _______________ interference builds the waves up causing bright patches

Diffraction of light• Light is ________________ radiation with a very ________

wavelength (400-700 nm)

• Light waves can be ____________ when they pass through

very small gaps (50 m) and can _____________ when they

overlap

Draw the laser diffraction pattern you saw in the box above

Diffraction of light

You can stick you ‘rainbow’ here

Path difference• Path difference is the

difference in how far the waves have traveled

• Even number of 1/2 wavelengths = constructive

• Odd number of 1/2 wavelengths = destructive

Polarisation

• Light waves are an

example of

____________ waves

• Not only do the go up

and down, they also

go ______ to ______

and in all other

directions

Polarisation - Polarising filters

Polarising filters• Polaroid plastic

polarises light so that only the vibrations in either the __________ or the ___________ direction are allowed to pass

• If two polarising filters are crossed then…

Polarisation - 3D movies