Science: Light

Question 1

What are the seven types of electromagnetic radiation?

Answer 1

radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

Question 2

How can radio waves be used?

Answer 2

used for broadcasting radio and TV signals

Question 3

how can microwaves be used?

Answer 3

used for heating food in microwave ovens.

Question 4

how can infrared radiation be used?

Answer 4

used in remote controls and night vision cameras.

Question 5

how can visible light be used?

Answer 5

lets us see and is used in lamps and torches.

Question 6

how can ultraviolet radiation be used?

Answer 6

used to sterilise equipment and kill germs.

Question 7

How can X-rays be used?

Answer 7

used to see inside the body for medical scans.

Question 8

How can gamma rays be used?

Answer 8

used to treat cancer.

Question 9

Which electromagnetic wave has the highest frequency, highest energy, lowest frequency and lowest energy?

Answer 9

Highest frequency: Gamma rays
Highest energy: Gamma rays
Lowest frequency: Radio waves
Lowest energy: Radio waves

Question 10

At what speed do the various energy levels of the electromagnetic spectrum travel?

Answer 10

They travel at the same speed (the speed of light)

Question 11

List the order of the colours in the visible spectrum. Know which ones have the longest and shortest wavelengths.

Answer 11

Red → Orange → Yellow → Green → Blue → Indigo → Violet
Longest wavelength: Red
Shortest wavelength: Violet

Question 12

diagram of a wave includes:

Answer 12

wavelength, amplitude, frequency, crest and trough.

Question 13

What is the Law of Reflection?

Answer 13

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

Question 14

Know the difference between regular and diffuse reflection.

Answer 14

Regular (Specular): Smooth surface, light reflects evenly, clear virtual image, angle in = angle out.

Diffuse: Rough surface, light scatters, no clear image, good for spreading light.

Question 15

Describe how the path of light changes when it passes through different transparent media.

Answer 15

More dense moves
Towards the normal
Less dense moves
Away from the normal

Question 16

What is a converging and diverging lens?

Answer 16

Converging: What it does: Brings light rays together to a point (focal point).
Diverging: What it does: Spreads light rays apart, as if coming from a point.

Question 17

How does light bend through converging and diverging lenses? Where are the focal points when light passes through each of these lenses?

Answer 17

Converging Lens (Convex)
- How light bends: Parallel light rays bend inward toward the center of the lens.
- Focal point (F): The point on the opposite side of the lens where all the rays meet.
- Example: A flashlight beam focused to a point.

2. Diverging Lens (Concave)
   - How light bends: Parallel light rays bend outward away from the center of the lens.
   - Focal point (F): The point on the same side as the incoming light from which the rays appear to come.
   - Example: Light spreading out from a peephole lens.

Question 18

What are real and virtual images?

Answer 18

Real image:
- What it is: An image that can be projected onto a screen.
- How it forms: Light rays actually meet at a point after reflecting off a mirror or passing through a lens.

Virtual image:
- What it is: An image that cannot be projected onto a screen.
- How it forms: Light rays don’t actually meet; they only appear to come from a point.

Question 19

Use the principles of refraction to explain why objects appear different underwater.

Answer 19

Objects appear different underwater because light bends (refracts) when it passes from water to air. This makes objects look closer and larger than they really are.

Question 20

Explain how we see colour.

Answer 20

We see colour because objects absorb some colours of light and reflect others. The reflected light enters our eyes, and our brain interprets it as the object’s colour. For example, a red apple reflects red light and absorbs the rest.

Question 21

the function of each part of the eye
(Cornea, Pupil, Iris, Lens, Retina,
Optical Nerve, Sclera,
Vitreous Humour)

Answer 21

Cornea: Clear front window; refracts + focuses light.

Pupil: Hole in iris; lets light in.

Iris: Coloured; changes size to control light entry.

Lens: Refracts light; focuses on retina; shape changed by ciliary muscles.

Retina: Rods & cones turn light into nerve impulses.

Optic nerve: Sends retina signals to brain.

Sclera: White outer layer; protection. Choroid: Black, blood vessel layer.

Vitreous humour: Watery front, jelly back; keeps shape; light medium.

Question 22

What parts of the eye will a light ray pass through to strike the retina?

Answer 22

the cornea, the pupil, the lens, and the vitreous humor

Question 23

How does the eye change in bright light or darkness? Explain why this occurs and which parts of the eye are involved.

Answer 23

• In bright light, the pupil gets smaller (contracts) to reduce the amount of light entering the eye. This protects the retina from too much light.
• In darkness, the pupil gets bigger (dilates) to let in more light, helping you see better.