3.17 describe experiments to investigate the refraction of light, using rectangular blocks, semicircular blocks and triangular prisms

3.17 describe experiments to investigate the refraction of light, using rectangular blocks, semicircular blocks and triangular prisms

As a light ray passes from one transparent medium to another, it bends. This bending of light is called refraction. Refraction occurs due to having different speed of light in different medium. For example, light travels slower in glass than in air. When ray of light travels from air to glass, it slows down as it crosses the boundary between two media. The change in speed causes the ray to change direction and therefore refraction occurs. Example:

The light bends towards the normal as it passes from low-density to high-density(air to glass). The light is refracted and upon emerging from the glass the light bends away from the normal as it passes high density to low-density (glass to air).

Experiment: To demonstrate the refraction of light through a piece of glass block.

Apparatus: Rectangular glass block with one face frosted, two rays boxes, piece of paper, protractor.

Procedure:

1. Place the glass block on a piece of paper with the frosted side down.
2. Send two narrow rays of light through the glass block as shown in Figure.
3. Observe the paths of the two rays of light.
4. Vary the angle of incidence i and measure the angle of refraction r using protractor.