Light

Light

by Aanisa Riyaz

​Reflection of Light

• ​We can observe the reflection of light in a ray diagram.

• ​You should be able to identify the normal, the angle of incidence, the angle of reflection and their respective incident and reflected rays.

• ​The angle of incidence will always be equal to the angle of reflection. (i=r)

Multiple Choice

Calculate the angle of incidence for the following diagram.

• 55 $$\degree$$  

• 27.5 $$\degree$$  

• 35 $$\degree$$  

• 25 $$\degree$$  

Multiple Choice

What is the law of reflection?

• Reflected ray = refracted ray

• Angle of reflection is equal to angle of refraction

• Angle of incidence is equal to angle of refraction

• Angle of incidence is equal to angle of reflection

​Image in a plane mirror

​In a plane mirror, light is reflected off the mirror surface and the image has the following features.

• ​Appears to be behind the mirror

• ​Is upright

• ​Laterally inverted

• ​Same size as object

Multiple Choice

What is the difference between the man standing in front of the mirror and the image in the mirror?

• Image is bigger

• Image is inverted

• Image is smaller

• Image is upside down

​Refraction of Light

• ​When light waves move from one medium to another (for example : from a solid such as glass to a liquid such as water), their speed changes and so does their direction. This is because different mediums have different densities.

• ​The denser the medium, the slower the light wave and lower refraction of light so the wave bends towards the normal

• ​Light waves refract more in a less dense medium and have a higher speed.

Multiple Choice

What does the image show?

• Reflection

• Refraction

• Loudness

• Frequency

Multiple Choice

This refraction happens because :

• Water is denser than air

• Air is denser than water

Multiple Choice

Speed of light in air is greater than speed of light in water.

• True

• False

Fill in the Blanks

When light moves from glass to air, speed of light

Fill in the Blanks

When light moves from air into water, the light ray bends

(closer/further away) from normal.

​Telescope

Submarines have periscopes which use the reflection of light to view things above water. Light rays from the object are reflected by the first mirror and then by the second mirror and reach the viewer's eye.

​Binoculars work much the same way.