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
