5.7 The diffraction grating Flashcards
1
Q
Define diffraction grating
A
a plate with many closely ruled parallel slits on it
2
Q
Why is light transmitted by the grating in certain directions only?
A
- light passing through each slit is diffracted
- the diffracted light waves from adjacent slits reinforce each other in certain directions only, including the incident light direction and cancel out in all other directions
3
Q
What causes the angle of diffraction between each transmitted beam and central beam to increase?
A
- light of a longer wavelength is used
- grating with closer slits is used
4
Q
What equation is used for diffraction grating?
A
dsinθ=nλ
5
Q
What creates a bigger angle of diffraction?
A
For a given order and wavelength, the smaller the value of d, the greater the angle of diffraction.
The larger the number of slits per metre, the bigger the angle of diffraction.
6
Q
How do you calculate the number of maxima observed?
A
2n+1, where n is the greatest order
