5.6 Diffraction

Question 1

Define diffraction

Answer 1

the spreading of waves when they pass through a gap or round an obstacle

Question 2

What makes diffracted waves spread out more?

Answer 2

1. gap is made narrower

2. the wavelength is made larger

Question 3

Describe the fringe pattern from a single slit

Answer 3

• The central fringe is twice as wide as each of the outer fringes
• The peak intensity of each fringe decreases with distance from the centre
• Each of the outer fringes is the same width
• The outer fringes are much less intense than the central fringe

Question 4

What equation is used to prove single slit diffraction?

Answer 4

w= (wavelength of light/ width of single slit) x 2D

Question 5

Why can no interference pattern be seen if the slits are too wide?

Answer 5

Because interference can only occur if the light from the 2 slits overlap.