Light and the electromagnetic spectrum

Question 1

What is the law of reflection?

Answer 1

angle of incidence = angle of reflection

Question 2

What is the normal?

Answer 2

An imaginary line that’s perpendicular to the surface at the point of incidence

Question 3

What is total internal reflection?

Answer 3

When a wave is reflected back into a material

Question 4

What are the two conditions needed for total internal reflection?

Answer 4

1) The angle of incidence must be greater than the critical angle.
2) The wave must be travelling from a more dense substance into a less dense one.

Question 5

What happens to a wave at a boundary if the angle of incidence is equal to the critical angle?

Answer 5

It would go along the surface that it hit

Question 6

What is specular reflection?

Answer 6

When waves are reflected in a single direction by a smooth surface

Question 7

What is diffuse reflection?

Answer 7

When waves are reflected in all directions by a rough surface

Question 8

What does the colour of an opaque object depend on?

Answer 8

Which wavelengths of light it reflects

Question 9

If white, blue and red light through a red filter, how will each colour look?

Answer 9

White > Red
Blue > Black
Red > Red

Question 10

If the focal length of a lens is shorter, the power of the lens is what?

Answer 10

Greater

Question 11

If the curvature of a lens increases, what happens to the power of the lens?

Answer 11

It also increases

Question 12

Understand ray diagrams

Answer 12

Pg 42 in CGP

Question 13

What does a converging lens look like?

Answer 13

It bulges outwards in the middle

Question 14

What does a diverging/concave lens look like?

Answer 14

It caves inwards

Question 15

How does a converging lens affect light rays?

Answer 15

It brings them together at the principal focus

Question 16

How does a diverging lens affect light rays?

Answer 16

It causes them to spread out

Question 17

Where is the principal focus of a diverging lens?

Answer 17

Where the rays appear to all come from

Question 18

What is a real image, can it be captured on a screen and what type of lens is needed to form one?

Answer 18

A real image is formed when the light rays actually come together to form the image. It can be captured on a screen. It is formed by a converging lens.

Question 19

What is a virtual image, can it be captured on a screen and what type of lens is needed to form one?

Answer 19

A virtual image is when the light rays from the object appear to be coming from a completely different place to where they’re actually coming from. It cannot be captured on a screen. It is formed by a diverging lens.

Question 20

Are electromagnetic waves transverse or longitudinal?

Answer 20

They are all transverse

Question 21

When do all electromagnetic waves travel at the same speed?

Answer 21

When they are in a vacuum

Question 22

All electromagnetic waves transfer energy from a source to an observer, give an example that shows this

Answer 22

When you warm yourself by an electric heater infrared waves transfer thermal energy from the heater (the source) to you (the observer)

Question 23

Name the 7 main groupings of electromagnetic waves from longest wavelength to shortest

Answer 23

Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays

Question 24

Name the 7 main colours of the visible light spectrum from longest wavelength to shortest

Answer 24

Red, orange, yellow, green, blue, indigo, violet

Question 25

Which groupings of the electromagnetic spectrum can we detect with our eyes?

Answer 25

Only visible light

Question 26

In what 4 different ways can electromagnetic waves react at a boundary?

Answer 26

They can be absorbed, transmitted, refracted or reflected