7.5 Refraction: Air and Glass

Question 1

What is the difference between reflection and refraction?

Answer 1

Reflection is the phenomena where light incident on a surface bounces back into the medium it was travelling in whereas refraction is phenomena where light travelling through media of different densities deviates or bends from its original path.

Question 2

What is needed in writing an answer on the real life instances?

Answer 2

1. Intro statement from the question.
2. Rays of light from ________ beneath the __________ travel towards the ___________ interface.
3. Due to the change in optical density of the medium the speed of light increases/decreases.
4. As a result, it bends ________ from the normal at the point of incidence and undergoes refraction.
5. The observer perceives these rays of light converging at a lesser depth than the _____actuallyis

Question 3

A coin is placed under a glass block and appears to be shifted from its original position. Justify.

Answer 3

When a coin is placed under a glass block, it appears to be bent. Rays of light from the coin beneath the travel towards the glass-air interface. Due to the change in optical density of the medium, the speed of light increases. As a result, it bends away from the normal, and undergoes refraction. The observer perceives these rays of light converging at a lesser depth than the coinactuallyis.

Question 4

A pencil is placed in a glass of water and appears to be bent. Justify.

Answer 4

When a pencil is placed in a glass of water and appears to be bent. Rays of light from the pencil beneath the water travel towards the water-air interface. Due to the change in optical density of the medium, the speed of light increases. As a result, it bends away from the normal, and undergoes refraction. The observer perceives these rays of light converging at a lesser depth than the pencilactuallyis.

Question 5

What it total internal reflection?

Answer 5

When a ray of light is travelling from a denser to rarer medium, the angle of refraction gradually increases with the increase in the angle of incidence. Eventually there comes a point where the angle of refraction is 90° and the refracted ray scrapes past the interface.

The corresponding angle of incidence is known as the critical angle of incidence for that medium. An angle of incidence greater than the critical makes the light bend more than 90°, and hence it enters the denser materialsitcamefrom. This phenomena is called total internal reflection

Question 6

What happens when light is incident along the normal?

Answer 6

When light is incident along the normal, its angle of incidence is 0 degrees and so, it does not deviate from its path as it is already on the shortest path through the medium.

Question 7

What is the interface?

Answer 7

The interface is the boundary between two medium.