1. DIFFRACTION OF LIGHT
DIFFRACTION OF LIGHT

2. INTERFERENCE When two light sources interfere with each other.
Light intensity is reinforced at bright bands.
Light intensity is lost at dark bands

3. Iridescence- interference of light produced by a thin layer of a substance on a surface

4. DIFFRACTION
Producing an interference pattern with only one light source. Light rays move around a barrier and interfere producing bright bands and dark bands.

5. DIFFRACTION
Ridges in feather diffract white light, separating it into different colors.
Small grooves on CD diffract light.

6. DOUBLE SLIT DIFFRACTION
Constructive interference
Constructive interference
m=0
Destructive interference
Destructive interference

8. FORMULA λ/d = x/L λ = wavelength (m) d = distance between slits (m)
X = distance from central maximum to
first order bright line (m)
L = distance from the slits to the
screen (m)

9. Sample problem
First order image X
light
λ λ λ
Central Maximum
Light falls on 2 slits that are 1.9 x 10-4cm apart. A first order bright line is formed 22cm from the central maximum. The distance from the slits to the screen is 60cm.

10. A) Find the wavelength of light
L = 60cm =0.6m
x = 22cm = 0.22m
d = 1.9 x 10-4cm = 1.9 x 10-6m
λ/d = x/L
λ / 1.9 x 10-6 = 0.22 / 0.6
0.6λ = 4.18 x 10-5
λ = 6.96 x 10-7m

11. B) What color light is it?
Use v = f λ v = 3.0 x 108m/s
λ = 6.96 x 10-7m
3.0 x 108m/s = f (6.96 x 10-7m)
f = 4.3 x 1014Hz
Red light