PAG 5.4 - Determining Wavelength Using Diffraction from a CD

Question 1

What equation relates wavelength of a light source to the angle of diffraction?

Answer 1

λ = dsinθ

Question 2

What happens to light as it passes through a slit?

Answer 2

Light diffracts with max diffraction occurring when slit spacing matches light’s wavelength

Question 3

Describe the diffraction pattern observed from a CD reflection?

Answer 3

Series of coloured concentric circles with red on outside and violet inside

Question 4

What procedure is carried out to get the required frequency of light on the edge of the CD?

Answer 4

CD moved relative to the eye until the circle of the required frequency of light sits on the diameter of the CD

Question 5

What are the two measurements that are recorded?

Answer 5

Distance between eye and CD
Radius of the CD

Question 6

How can you calculate angle of diffraction

Answer 6

tanθ = r/D

Question 7

How can uncertainty in these values of wavelengths be found?

Answer 7

By comparing them to the accepted value of wavelengths of coloured LEDs