Y8 Science | Light

Question 1

Define luminous

Answer 1

Something that gives out light

Question 2

How do we see?

Answer 2

Light reflects off objects into our eyes

Question 3

Define reflect

Answer 3

When light bounces off a surface

Question 4

Define transparent

Answer 4

Material that allows all light to pass through it

Question 5

Define translucent

Answer 5

Material that allows some light to pass through it

Question 6

Define opaque

Answer 6

Material that allows no light to pass through

Question 7

State the speed of light

Answer 7

300,000km/s

Question 8

What can light travel through?

Answer 8

Anything that is not opaque; air, liquids, solids, a vacuum

Question 9

How do solar eclipses happen?

Answer 9

The Sun’s light is blocked when the Moon is directly between the Sun and the Earth, making a shadow

Question 10

How do lunar eclipses happen?

Answer 10

When the Earth is between the Sun and the Moon, it casts a shadow on the Moon

Question 11

What is a plane mirror?

Answer 11

A flat mirror

Question 12

Name the type of diagram used to show how light travels

Answer 12

Ray diagram

Question 13

What is the law of reflection?

Answer 13

Angle of incidence=angle of reflection

Question 14

Define incident ray

Answer 14

The incoming ray

Question 15

Define normal line

Answer 15

Line at right angles to the surface, from which angles are measured

Question 16

Define scattering

Answer 16

When light bounces off an object in all directions

Question 17

What is specular reflection?

Answer 17

Reflection from a smooth surface e.g. a mirror, produces an image

Question 18

What is diffuse scattering?

Answer 18

Reflection from a rough surface.

Question 19

How does light travel?

Answer 19

In straight lines

Question 20

Define refraction

Answer 20

Change of direction of light going from one material into another

Question 21

What does focus mean?

Answer 21

Bringing light rays together to a single point, needed to create a clear image e.g. in eye/photo

Question 22

Define convex lens

Answer 22

Lens that brings parallel rays together to a focus point. Thicker at the centre than at the edges

Question 23

What is a focal point?

Answer 23

the place where rays in a ray diagram cross

Question 24

Name five parts of the eye

Answer 24

Iris, Pupil, Lens, Retina, Optic nerve

Question 25

State the function of the retina

Answer 25

Layer at the back of the eye with light-detecting cells and where an image is formed

Question 26

State the function of the pupil

Answer 26

Hole in the middle of the iris that allows light to pass through and enter the eye

Question 27

State the function of the lens

Answer 27

Refracts light to focus on the retina

Question 28

State the function of the optic nerve

Answer 28

Carries electrical signals to the brain

Question 29

What is a pinhole camera?

Answer 29

A box with a hole on one side, translucent screen on the other, produces upside down image

Question 30

How are cameras and eyes similar?

Answer 30

Photosensitive (light sensitive) material, light absorbed and a chemical/electrical signal produced

Question 31

How do light and sound waves differ?

Answer 31

Sound is longitudinal/light is transverse, sound needs matter to travel through

Question 32

Define spectrum

Answer 32

Band of colours of the rainbow made when white light is separated

Question 33

How can white light be separated?

Answer 33

Using a prism

Question 34

What are the primary colours (of light)

Answer 34

red, green, blue (can use to make any other colour)

Question 35

What do filters do to light?

Answer 35

They only let light of that colour pass through - the rest are absrobed

Question 36

Define absorption

Answer 36

When energy is transferred from light to a material

Question 37

Define transmit

Answer 37

When light passes through something

Question 38

Why do some objects appear coloured?

Answer 38

The colour seen is reflected by the object, all the other colours are absorbed