## Saturday, 6 September 2014

### DIFFRACTION 1 PROBLEMS

DIFFRACTION 1

Where necessary take the velocity of light as = 3x108 ms-1 and the velocity of sound as 330ms-1

1. Red monochromatic light falls on a narrow slit. Describe what happens to the diffraction pattern as the slit is slowly opened.

2. How would the diffraction pattern in number one be affected if blue light were used instead of red?

3. Which would be easier to receive in hilly areas and why, television or radio?

4. Why is the diffraction of light much more difficult to observe than the diffraction of microwaves?

5. A diffraction grating has 300 lines per mm.
Calculate:
(a) the angle of diffraction for the first order image for light of wavelength 550 nm
(b) the highest order possible with this grating at this wavelength
(c) the number of images of the source

6. Calculate: (a) the grating spacing for light of wavelength 500 nm passing through a grating where the angle of diffraction for the second order image is 20.5o
(b) the number of lines per millimetre on the grating