Chapter 5 : Ray Model of Light

Question 1

How do luminous objects allow us to see them?

Answer 1

They emit light in all directions. Light then travels in straight lines from these objects to our eyes. Thus, we are able to see the objects.

Question 2

Define reflection.

Answer 2

It is the bouncing of light off a surface.

Question 3

What is the surface of a plane mirror like?

Answer 3

It is smooth and flat.

Question 4

How many characteristics of plane mirrors are there?

Answer 4

5

Question 5

What are the 5 characteristics of images formed by plane mirrors?

Answer 5

1. The image is the same size as the object.
2. The image is upright
3. The image is virtual ( the image is formed inside the mirror and thus is unable to be formed on a screen
4. The image is laterally inverted (reverses right and left sides of an image)
5. The distance between the object and the mirror is the same as the distance between the image and the mirror.

Question 6

What are the five parts needed to form a ray model of light?

Answer 6

1. Incident ray
2. Reflected ray
3. Normal
4. Angle of incidence
5. Angle of reflection

Question 7

What is a special characteristic for the angle of incidence and reflection?

Answer 7

The angle of incidence is always equal to the angle of reflection.

Question 8

What are the 2 types of curved mirrors?

Answer 8

Concave and Convex mirrors

Question 9

Convex mirrors curve ______

Answer 9

outwards

Question 10

Concave mirrors curve ______

Answer 10

inwards

Question 11

What are the 3 characteristics of images formed by convex mirrors?

Answer 11

1. The image is upright
2. The image is virtual
3. The image is diminished

Question 12

Convex mirrors provide a _________________________________

Answer 12

a wider field of vision

Question 13

When are convex mirrors commonly used?

Answer 13

They are commonly used when a large area needs to be seen.

Question 14

What are the benefits of placing convex mirrors at road junctions?

Answer 14

They allow drivers to see around blind corners, giving them more time to respond to oncoming traffic.

Question 15

What are the benefits of installing convex mirrors at the corner of some shops?

Answer 15

They allow shopkeepers to see a large area from a single location.

Question 16

What are the benefits of using convex mirrors as rear and side view mirrors of cars?

Answer 16

They enable drivers to see a large area of the traffic behind them.

Question 17

What are the 3 characteristics of images formed by concave mirrors?

Answer 17

1. The image is upright
2. The image is virtual
3. The image is magnified

Question 18

What are the benefits of using a concave mirror as a dentist mirror?

Answer 18

They allow dentists to examine the teeth closely.

Question 19

What are the benefits of using a concave mirror as cosmetic mirror?

Answer 19

It forms a magnified image of our face, allowing us to shave or apply make-up more easily

Question 20

What are the benefits of using concave mirrors in the headlights of a car?

Answer 20

They reflect the light from the bulbs in the headlights to form strong beams of light, thus lighting up the road ahead.

Question 21

What are the benefits of placing a concave mirror at the base of a microscope?

Answer 21

It reflects light from the lamp of the microscope to a specimen, allowing us to view the magnified image of the specimen.

Question 22

How is each light ray reflected when they fall on a smooth surface?

Answer 22

When parallel rays of light fall on a smooth surface, each ray is reflected in the same direction.

Question 23

_____ images are formed when reflection on smooth surfaces occurs.

Answer 23

Clear

Question 24

How is each light ray reflected when they fall on a rough surface?

Answer 24

When parallel rays of light fall on a rough surface, each ray is reflected in a different direction.

Question 25

Why are we unable to see our reflection on rough surface?

Answer 25

Since rough surfaces scatter light, we are unable to see our reflection on a rough surface

Question 26

Define refraction.

Answer 26

Refraction is the bending of light at the boundary between two different transparent mediums due to a change in the speed of light as it passes from one material into the other which is caused by optical density

Question 27

What physical property does an optical medium have?

Answer 27

Optical density

Question 28

What does optical density do?

Answer 28

It affects the speed at which light travels through the medium.

Question 29

What does it mean if the refracted ray bends towards the normal?

Answer 29

It means that the optical medium that it is travelling through is denser than the first one.

Question 30

What does it mean if the refracted ray bends away from the normal?

Answer 30

It means that the optical medium that it is travelling through in less dense than the first one.

Question 31

What happens when the light ray enters the next optical medium perpendicularly?

Answer 31

There will be no bending of light as there is no angle of incidence, meaning that there is also no angle of refraction. However, the speed of light still decreases in the denser optical medium.

Question 32

Refraction can make swimming pools appear ______ than they actually are

Answer 32

shallower

Question 33

What colors are white light made up of?

Answer 33

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

Question 34

Which color light bends the most?

Answer 34

Violet light.

Question 35

Which color light bends the least?

Answer 35

Red light.

Question 36

Define dispersion.

Answer 36

Dispersion is the splitting of white light into its component colors.

Question 37

How can infrared radiation be used?

Answer 37

It can be used in healthcare.

Question 38

What are the harmful effects of infrared radiation?

Answer 38

Overexposure to infrared radiation can harm us. Workers who have prolonged exposure to infrared radiation must wear goggles to protect their eyes. Infrared radiation trapped in the atmosphere contributes to climate change.

Question 39

How can ultraviolet radiation be used?

Answer 39

We can use it disinfect medical equipment and it is also an environmentally friendly method.

Question 40

What are the harmful effects of ultraviolet radiation?

Answer 40

Overexposure to UV radiation can harm our eyes and cause skin cancer.

Question 41

Why do we need to apply sunscreen?

Answer 41

It helps to filter put UV radiation

Question 42

How is visible light used?

Answer 42

Plants rely on the energy provided by visible light to make sugars using carbon dioxide and water through photosynthesis. Visible light also allows us to carry out our daily activities.

Question 43

What are the harmful effects of visible light?

Answer 43

Visible light can cause chemical changes in some materials and can also cause light pollution.

Question 44

What happens when visible light causes chemical changes in some materials?

Answer 44

It will result in the deterioration of their quality.

Question 45

What happens when visible light causes light pollution?

Answer 45

Light pollution negatively impacts living things that depend on Earth’s cycle of day to carry out life-sustaining activities such as migration, reproduction, searching of food, sleeping and escaping from predators.