Explanation
In general, light travels in a straight line. We can see this phenomenon from our
experiment. The laser beam from the laser pointer goes straight to the screen.
However, light can be refracted when it travels through mediums with different
refractive indices, for example water. From our experiment, when we put a glass of
water between the laser pointer and the screen, the laser is refracted. As a result, the
laser point on the screen shifts.
The rainbow in the sky is also caused by the refraction. Light travels from the sun and
is refracted by water drops in the air. Light contains many colours with different
wavelengths and each colour is refracted at a different angle. This causes the
dispersion of light and seen as a rainbow in the sky.