What happens when a beam of white light passes through the grating?
Assemble the experimental set-up shown in the diagram. See how the white light spectrum appears on the screen.
What we are doing here.
Again, we begin to study nature methodically. The method we need most for light phenomena is to study what happens to a single ray of light.Once we know this, we can often tell what happens when there are many rays of light.
In this experiment, the slit and the grating have been combined simply to make the experiment easier. But the idea remains the same: the slit is used to extract a narrow beam of light from the light source.
In the experiment, we learn that the lattice, or rainbow glasses, deflect the light beam away from the straight line. But, in a big difference from a mirror, for example, the grating deflects different coloured light away from the straight line to a different extent. Red more, blue least. This is how a rainbow is formed.
