3C.1 Refraction

Question 1

What is refraction?

Answer 1

A change in direction of a wave when it passes from one medium to another due to a change in speed.

Question 2

What happens to speed, wavelength, and frequency when light enters a different medium?

Answer 2

Speed changes, wavelength changes, frequency stays constant.

Question 3

Why does refraction occur?

Answer 3

Because wave speed changes in different media.

Question 4

What is the refractive index (n)?

Answer 4

n = c/v, where c is the speed of light in vacuum and v is the speed of light in the material.

Question 5

What is Snell’s Law?

Answer 5

n₁ sinθ₁ = n₂ sinθ₂, where θ₁ and θ₂ are measured from the normal.

Question 6

How does light bend when entering a denser medium?

Answer 6

It bends towards the normal.

Question 7

How does light bend when leaving a denser medium?

Answer 7

It bends away from the normal.

Question 8

What is the normal in refraction?

Answer 8

A line drawn perpendicular to the boundary between two media.

Question 9

How can refractive index be measured experimentally?

Answer 9

Measure the angle of incidence and angle of refraction and apply Snell’s Law.

Question 10

What graph can be used to determine refractive index?

Answer 10

Plot sinθ₂ vs sinθ₁; the gradient equals the reciprocal of the refractive index.

Question 11

What is dispersion?

Answer 11

The splitting of white light into its component colours.

Question 12

Why does dispersion occur?

Answer 12

Different wavelengths refract by different amounts in a material.

Question 13

Which colour refracts most in a prism?

Answer 13

Violet light.

Question 14

Which colour refracts least in a prism?

Answer 14

Red light.

Question 15

What two equations must be remembered for refraction?

Answer 15

n = c/v and n₁ sinθ₁ = n₂ sinθ₂.