Thomas Young performed an experiment in the early 19th century that proved light has wave properties by demonstrating the double-slit interference pattern. The experiment showed that light passing through two slits results in a pattern of bright and dark bands on a screen due to the constructive and destructive interference of the light waves. The angles of constructive and destructive interference can be calculated using equations that relate the wavelength, slit separation distance, and interference order.

1. {
Double-Slit
Interference
By Mike Yoon
Physics 101 203
14334149

2.  Early 19th century, Thomas Young performed
an experiment that proved light has wave
properties.
History

3. Visual representation of
the experiment

4.  The waves in the picture represent the peak of a
wave.
 When these peaks overlap another peak, the
wave is exactly in phase.
 The straight lines in the picture represent bright
spots due to the constructive interference from
the peaks and valleys overlapping.

5.  Since the waves from the two slits are from the
same light source, the waves are exactly in sync
but comes out in different holes.
 Therefore only a phase difference differs from
these two waves.

6.  The constructive interference occurs when
dsin(theta) = m times wavelength
 The destructive interference occurs when
dsin(theta) = (m+ ½) times wavelength
 Where m is an interger
 d is the distance between two slits.
 Theta is the angle that the bright spot appears
on the screen.

7.  https://www.youtube.com/watch?v=Pk
6s2OlKzKQ&spfreload=10
Great youtube video on
Double-Slit Interference

8.  1. The distance between the two slits are
2.56 x 10^-5 m, the wave length is 550 nm while
m is 1. Find the angle of the constructive and
destructive points.
Practice problems

9.  Theta = 0.021486 rad
Answers