Waves: Diffraction

1. Learning Objectives Book Reference : Pages 202-204 Waves: Diffraction To understand diffraction To understand how waves pass through a single slit To undertake a virtual microwave diffraction experiment and to produce a good quality graph

2. Diffraction is the spreading of waves when they pass through a gap, past an edge or around a corner Diffraction is a general property of all waves Diffraction : Definition

3. We can use a ripple tank to demonstrate diffractions of waves in water. What effect on the spread of the waves does the following have? The gap is made narrower The wavelength is increased? Diffraction : Ripple Tank Notebook animations

4. We can observe diffraction using a single slit. The characteristic spreading out pattern is observed Diffraction : Single slit 1 Huygens animations

5. When the single slit diffraction pattern is observed on a screen, we see a characteristic fringe pattern. Diffraction : Single slit 2 Note that the fringes reduce in intensity the further you are away from the centre and that the centralfringe is double the width

6. Diffraction : Single slit 3

7. Red light from a laser is directed normally at a slit that can be adjusted in width. The diffracted light forms a pattern of diffraction fringes on a white screen. Describe how the appearance of the fringes change if the slit is made wider Problems 1