5.1- REFRACTION OF LIGHT

Question 1

What theory can be used to explain reflection and refraction of light?

Answer 1

wave theory

Question 2

When we consider the effect of lenses or mirrors on the path of light, what do we usually prefer to draw diagrams using?

Answer 2

light rays and normals

Question 3

What do light rays represent?

Answer 3

direction of travel of wavefronts

Question 4

What is the normal?

Answer 4

imaginary line perpendicular to a boundary between to materials or a surface

Question 5

What is refraction?

Answer 5

change of direction that occurs when light passes at an angle across a boundary between two transparent substances

Question 6

Where would light ray bend towards when it passes from air into glass?

Answer 6

towards normal when it passes from air into glass

Question 7

Where would light ray bend towards when it passes from glass into air?

Answer 7

away from normal when it passes from glass to air

Question 8

When does no refraction take place?

Answer 8

if the incident light ray is along the normal

Question 9

At boundary between two transparent substances, where does light ray bend towards when it passes into more dense substance?

Answer 9

towards normal if it passes into a more dense substance

Question 10

At boundary between two transparent substances, where does light ray bend towards when it passes into less dense substance?

Answer 10

away from normal if it passes into a less dense substance

Question 11

Investigating the refraction of light by glass method?

Answer 11

use ray box to direct light ray into rectangular glass block at different angles of incidence at midpoint P of one of the longer sides

Question 12

What is the angle of incidence?

Answer 12

angle between incident light ray and normal at point of incidence

Question 13

What is the angle of refraction?

Answer 13

angle between the normal and refracted ray

Question 14

What does the measurements of the angles of incidence and refraction for different incident rays show? (2) (investigating the refraction of light by glass)

Answer 14

angle of refraction at P always less than angle of incidence

ratio of sin i / sin r same for each light ray

Question 15

What is the ratio of sin i / sin r known as?

Answer 15

Snell’s law

Question 16

What is the ratio sin i / sin r referred to as?

Answer 16

refractive index

Question 17

For light ray travelling from air into transparent substance, how is the refractive index of the substance worked out?

Answer 17

sin i / sin r

Question 18

What else occurs when a light ray in air enters glass (or any other refractive substance)?

Answer 18

partial reflection

Question 19

Why would the angle of refraction of light ray emerging from block be same as angle of incidence of light ray entering block?

Answer 19

two sides of block at which refraction occurs are parallel to each other

Question 20

Refraction of light ray by triangular prism

Answer 20

light ray refracts towards normal where it enters glass prism then refracts away from normal where it leaves prism