Topic 14 - Light

Question 1

What is the angle of incidence?

Answer 1

Angle between the incident ray and the normal line.

Question 2

What is the angle of reflection?

Answer 2

Angle between the reflected ray and the normal line.

Question 3

What is a concave lens?

Answer 3

A lens that makes parallel rays diverge.

Question 4

What is a convex lens?

Answer 4

A lens that makes light rays parallel to the principal axis converge at a point.

Question 5

What is diffuse reflection?

Answer 5

Reflection from a rough surface and thus the light rays are scattered in different directions.

Question 6

What is the focal length?

Answer 6

The distance from the centre of a lens to the point where light rays parallel to the principal axis are focused, or in a divergent lens, diverge from.

Question 7

What is the equation for magnification?

Answer 7

The image height / the object height.

Question 8

What is the normal?

Answer 8

A straight line through a surface or boundary perpendicular to the surface or boundary.

Question 9

What is an opaque object?

Answer 9

An object that light cannot pass through.

Question 10

What is the principal focus?

Answer 10

The point where light rays parallel to the principal axis of a lens are focused, or in a diverging lens, divert from.

Question 11

What is a real image?

Answer 11

An image formed by a lens that can be projected onto a screen.

Question 12

What is refraction?

Answer 12

The change of direction of a light ray when it passes across a boundary between two transparent substances.

Question 13

What is specular reflection?

Answer 13

Reflection from a smooth surface. Each light ray is reflected in a single direction.

Question 14

What is a translucent object?

Answer 14

An object that allows light to pass through, but the light is scattered or refracted.

Question 15

What is a transparent object?

Answer 15

An object that transmits all the incident light that enters the object.

Question 16

What is a virtual image?

Answer 16

An image, seen in a lens or mirror, from which light rays appear to come after being refracted by a lens or reflected by a mirror.

Question 17

What is the law of reflection?

Answer 17

On reflection from a smooth surface, the angle of the reflected ray is equal to the angle of the incident ray.

Question 18

What is diffuse reflection?

Answer 18

The reflection of light from a surface such that an incident ray is reflected at many angles, rather than one.

Question 19

What is an incident ray?

Answer 19

A ray pointing towards and striking a surface.

Question 20

What is dispersion?

Answer 20

Separating colours into a rainbow.

Question 21

What does light consist of?

Answer 21

Waves.

Question 22

What is true about reflected and incident waves?

Answer 22

They have the same frequency and travel at the same speed, so have the same wavelength.

Question 23

What is the normal?

Answer 23

The line perpendicular to the mirror.

Question 24

What is true about the relationship between the angle of incidence and angle of reflection?

Answer 24

They are equal

Question 25

What can an image displayed on a screen be described as?

Answer 25

A real image

Question 26

What is the change in direction of a light ray called?

Answer 26

Refraction

Question 27

What happens when light enters a more dense medium?

Answer 27

It is refracted towards the normal.

Question 28

What happens when light enters a less dense medium?

Answer 28

It is refracted away from the normal.

Question 29

What happens when light travels from air into glass?

Answer 29

It changes towards the normal.

Question 30

What happens when light moves from glass into air?

Answer 30

It changes direction away from the normal.

Question 31

What does the colour of light depend on?

Answer 31

The type of light source. Stars and lamps emit light that has a continuous range of wavelengths across the visible spectrum. Light sources like lasers and neon lamps emit a narrow range of wavelengths.

Question 32

What does the colour of an opaque object depend on?

Answer 32

Pigments and range of wavelengths in the incident light.

Question 33

What is true of a white surface?

Answer 33

It has no pigments so it reflects light of any wavelength.

Question 34

What is true of a red surface?

Answer 34

It has a pigment that absorbs all colours of light apart from red.

Question 35

What are transparent objects?

Answer 35

Objects that transmit all incident light that enters the object.

Question 36

What is a translucent object?

Answer 36

An object that lets light pass through it, but it is scattered or refracted.

Question 37

What is an opaque object?

Answer 37

An object that absorbs all the light that reaches it. Light is either reflected scattered or absorbed.

Question 38

What is the principle focus?

Answer 38

The point to which light is focused.

Question 39

What is a converging lens uses as?

Answer 39

A magnifying glass

Question 40

What is magnification equal to?

Answer 40

Image height / Object height

Question 41

What does the position and nature of an image depend on?

Answer 41

The focal length of the lens. The distance from the object to the lens.

Question 42

What is the prinicipal axis?

Answer 42

The straight line that passes along the normal at the centre of each lens surface.

Question 43

What is the distance from the lens to the film equal to?

Answer 43

The focal length of the lens.