Young's Double Slit Interference (AQA A Level Physics): Revision Note

Young’s double slit experiment demonstrates how light waves produced a diffraction pattern

The experimental setup and results are shown below

A monochromatic source was used to ensure that the two rays were coherent

• The resulting pattern on the screen showed an interference pattern

This was in disagreement with corpuscular theory, which would have predicted only two bright regions

• If paintballs were fired through two gaps at a wall, they would leave paint on only two separate regions of the wall

The only explanation for the interference pattern was that light diffracted through the thin slits, like a wave

• This was evidence in support of Huygens' wave theory of light

This experiment was definite evidence for the wave theory of light as opposed to the corpuscular theory

• Corpuscular theory, however, was not immediately rejected

It took further experiments for the scientific community to consider wave theory as the accepted theory of light

• The most important of these was Hippolyte Fizeau's experiment to determine the speed of light in water