refraction what has happened in each example and why? i think this is called...it happens when... it...

Refraction

What has happened in each example and why?I think this is called... It happens when...

It happens because... The air is...

The water is... The light usually travels...but when it hits water...

PAIRED TALKING

To know how light is refracted through different medium.

To know how light is refracted through different medium.

Success criteria-State why refraction happens.Describe the direction light is refracted in

different situations.Use the equation for refractive index.

TEAM WORKERS

To know how light is refracted through different medium.

Observations-• What do you notice about the angle of

refraction as the light ray enters the block (from air into glass)?

• What do you notice about the angle of refraction as the light exits the glass block (from glass into air)?

angle of incidence /

°

angle of refraction /

°

deviation / °

0

15

30

45

60

75

angle of incidence /

°

angle of refraction /

°

deviation / °

0

15

30

45

60

75

angle of incidence /

°

angle of refraction /

°

deviation / °

0

15

30

45

60

Observation

Face angle of incidence /

°

angle of reflection /

°

1

1

Observation

Rectangular block air into block

Rectangular block air into block

Semi circle block (block into air)

Prism (block into air)

How does Refraction work?• As the light enters a glass block or water it is

refracted (bent) when it enters and leaves the lens.

To know how light is refracted through different medium.

Refraction of light at a plane surface(a) Less to more optical dense transition (e.g. air to glass)

angle of incidence

normal

AIR GLASS

angle of refraction

Light bends TOWARDS the normal.

The angle of refraction is LESS than the angle of incidence.

(b) More to less optical dense transition (e.g. water to air)

angle of refraction

angle of incidence

normal

WATER AIR

Light bends AWAY FROM the normal.

The angle of refraction is GREATER than the angle of incidence.

2 different materials which have different densities. The more dense a material the more particles. Light can travel faster in air than it can in a liquid or solid so it slows down when entering them.

The Normal line is always 90° to the interface

The place where the 2 materials meet is called the interface

When the incident ray enters the glass block (doesn’t matter about shape!) the ray slows down and swings TOWARD the Normal line.

When the refracted ray or Emergent ray leave the glass block it speeds up again and swings AWAY FROM the Normal.

To know how light is refracted through different medium.

• www.upscale.utoronto.ca/PVB/Harrison/Flash/Optics/Refraction/Refraction.html

object at the bottom of a pool

AIR

WATER

Why a pool appears shallow

image

normals

observer

To know how light is refracted through different medium.

Complete the paths of the RED light rays:

AB

C

D

E

F

To know how light is refracted through different medium.

Complete the paths of the RED light rays:

AB

C

D

E

F

To know how light is refracted through different medium.

To know how light is refracted through different medium.

• Refractive index = sin i / sin r• Using the table of values below, calculate the refractive index of

the medium. Suggest which material the medium is made of.

Angle of Incidence

Angle of Refraction

Refractive Index

Material

24.0 15.7 24.0 9.76 24.0 18.2 63.0 36.4 47.0 29.2

Material Refractive Index

Glass 1.5Perspex 1.5Diamond 2.4Water 1.3

To know how light is refracted through different medium.

Success criteria-State why refraction happens.Describe the direction light is refracted in

different situations.Use the equation for refractive index.

TEAM WORKERS

To know how light is refracted through different medium.

1. Using the above equation calculate what the angle of incidence must have been to give the following angles of refraction in glass.

– 23°– 33°– 40°

2. A beam of light shines on a diamond block with an angle of incidence of 15°. Calculate the angle of refraction.

To know how light is refracted through different medium.