1.1. To understand diffractionTo understand diffraction

2.2. To understand how waves pass through a To understand how waves pass through a single slitsingle slit

3.3. To undertake a virtual microwave diffraction To undertake a virtual microwave diffraction experiment and to produce a good quality experiment and to produce a good quality graphgraph

Book Reference : Pages 202-204Book Reference : Pages 202-204

Diffraction is the spreading of waves when they Diffraction is the spreading of waves when they pass through a gap, past an edge or around a pass through a gap, past an edge or around a cornercorner

Diffraction is a general property of all wavesDiffraction is a general property of all waves

We can use a ripple tank We can use a ripple tank to demonstrate to demonstrate diffractions of waves in diffractions of waves in water.water.

What effect on the spread What effect on the spread of the waves does the of the waves does the following have?following have?

1.1.The gap is made The gap is made narrowernarrower

2.2.The wavelength is The wavelength is increased?increased? Notebook animations

We can observe We can observe diffraction using a single diffraction using a single slit. The characteristic slit. The characteristic spreading out pattern is spreading out pattern is observedobserved

Huygens animations

When the single slit diffraction pattern is When the single slit diffraction pattern is observed on a screen, we see a characteristic observed on a screen, we see a characteristic fringe pattern. fringe pattern.

Note that the Note that the fringes fringes reducereduce in in intensity the intensity the further you are further you are away from the away from the centre and that centre and that the the centralcentral fringefringe is is doubledouble the widththe width

Red light from a laser is directed normally at a Red light from a laser is directed normally at a slit that can be adjusted in width. The diffracted slit that can be adjusted in width. The diffracted light forms a pattern of diffraction fringes on a light forms a pattern of diffraction fringes on a white screen. Describe how the appearance of white screen. Describe how the appearance of the fringes change if the slit is made widerthe fringes change if the slit is made wider