Refraction

Question 1

What is refraction?

Answer 1

A change in the direction of a wave as it crosses a boundary.

Question 2

When does refraction occur?

Answer 2

As the wave enters a different medium and the change in speed causes a change in direction.

Question 3

For refraction it is important to note that ______ remains constant but ______ and ______ of the wave changes.

Answer 3

Frequency
Wavelength
Speed

Question 4

The more dense the wave the slower the _____.

Answer 4

Speed

Question 5

As we move into an optically dense medium the ____ and _____ of the wave decreases .

Answer 5

Speed

Wavelength

Question 6

What are the two rules for the direction in which the light ray refracts?

Answer 6

• Light ray travels from a less optically dense medium to a more optically dense medium, the light ray moves towards the normal.
• Light ray travels from a more optically dense medium to a less optically dense medium, the light ray moves away from the normal.

Question 7

What is the refraction index?

Answer 7

The refractive index of a medium,n, is the ratio of the speed of light in a vacuum to the speed of light in a medium.

Question 8

Speed of light in a vacuum

Answer 8

3 x 10^18 m/s

Question 9

The greater the refractive index of a particular medium, the _____ is the speed of light in the medium and as a result the light ______.

Answer 9

Slower

Bends

Question 10

Light travels in a _____.

Answer 10

Vacuum

Question 11

Speed of light

Answer 11

299 792 458 m/s

Question 12

What are the laws of refraction?(2)

Answer 12

• The incident ray, the reflected ray and the normal at the point of incidence all lies on the same plane
• refraction Index =sin i / sin r

Question 13

How can apparent depth be calculated?

Answer 13

Refractive index=real depth / apparent depth

Question 14

What is the critical angle?

Answer 14

The angle of incidence that provides an angle of refraction of 90 degrees.

Question 15

What is the angle of refraction?

Answer 15

Angle between the refracted ray and the normal.

Question 16

What happens when the angle of incidence is 0?

Answer 16

Ray emerges without deviation

Question 17

As the angle of incidence increases….

Answer 17

The angle of refraction of the emerging ray also increases.

Question 18

What happens when the angle of incidence is greater than the critical angle?

Answer 18

The ray is reflected. This is known as total internal reflection.

Question 19

What two conditions must be present for internal reflection to occur?

Answer 19

• Light ray must travel from an optically denser medium towards an optically less dense medium
• The angle of incidence must be greater than the critical angle

Question 20

How do you find the critical angle?

Answer 20

Sin c = 1/n