No Longer On Exam

Question 1

What type of spectrum do EM waves form?

Answer 1

A continuous spectrum.

Question 2

Order the types of EM waves/radiation from lowest to highest frequency

Answer 2

• Radio waves.
• Microwaves.
• Infrared.
• Visible light.
• Ultraviolet.
• X-rays.
• Gamma rays.

Question 3

How do the speeds to EM waves/radiation differ in a vacuum and in air?

Answer 3

Electromagnetic waves all travel at the same speed in a vacuum and in the air.

Question 4

What property of waves in different mediums causes refraction?

Answer 4

• Velocity.

- Wave speed is slower in denser materials, causing refraction.

Question 5

In which direction do waves refract when entering a denser medium?

Answer 5

• When entering a more dense medium, the wave slows down.
• This causes them to bend towards the normal.
• This lead to the angle of refraction being less than the angle of incidence.

Question 6

What type of waves can be produced by oscillations in an electrical circuit?

Answer 6

Radio waves.

Question 7

How can radio waves create an alternating current in a circuit?

Answer 7

When radio waves are absorbed, they can create oscillations in a circuit with same frequency as the radio waves creating AC.

Question 8

Where do gamma rays originate from?

Answer 8

They originate from changes in the nuclei of atoms.

Question 9

What health effects can ultraviolet waves cause?

Answer 9

• They can cause the skin to age prematurely.

- Increase risk of developing skin cancer.

Question 10

What health effects can X-rays and gamma rays cause?

Answer 10

• They are ionising radiation so can cause mutations in genes.
• They can lead to increased risk of developing various cancers.

Question 11

Give 3 practical uses for infrared radiation

Answer 11

• Electrical heaters.
• Cooking food.
• Infrared cameras.

Question 12

How can infrared be used for cooking food?

Answer 12

Infrared light has frequencies which are absorbed by some chemical bonds. The internal energy of the bonds increases when they absorb infrared light, which causes heating.

Question 13

Give 2 practical uses for microwave radiation

Answer 13

• Satellite communications.

- Cooking food.

Question 14

How can microwaves be used for cooking food?

Answer 14

High frequency microwaves have frequencies which are easily absorbed by molecules in food. The internal energy of the molecules increases when they absorb microwaves, which causes heating.

Question 15

How can microwaves be used for satellite communications?

Answer 15

Microwaves pass easily through the atmosphere, so they can pass between stations on earth and satellites in orbit.

Question 16

Give 2 practical uses for radio waves

Answer 16

• Television transmission.

- Radio transmission.

Question 17

Give a practical use for visible light

Answer 17

Fibre optic communications.

Question 18

What wave phenomenon is used by lenses to form an image?

Answer 18

Refraction.

Question 19

How does a convex lens form an image?

Answer 19

Parallel rays of light are refracted and brought together at a point known as the principal focus.

Question 20

What is meant by the focal length of a lens?

Answer 20

The distance from the lens to the principal focus.

Question 21

What is the difference between the image produced by a convex and a concave lens?

Answer 21

• Convex lenses can produce real or virtual images.

- Concave lenses can only produce virtual images.

Question 22

Why does magnification not have a unit?

Answer 22

• It is the ratio between image height and object height.

- Ratios do not require units.

Question 23

What symbol is used to represent a convex lens in a ray diagram?

Answer 23

↕

Question 24

What symbol is used to represent a concave lens in a ray diagram?

Answer 24

Similar to the convex, but arrows point towards the line.

Question 25

What determines the colour of visible light waves?

Answer 25

The wavelength and frequency of the light waves.

Question 26

What colour of visible light has the highest frequency?

Answer 26

Blue.

Question 27

What colour of visible light has the largest wavelength?

Answer 27

Red.

Question 28

What is meant by the term ‘specular reflection’?

Answer 28

Reflection from a smooth surface in a single direction.

Question 29

What is meant by the term ‘diffuse reflection’?

Answer 29

Reflection from a rough surface which causes scattering.

Question 30

How does a red colour filter work?

Answer 30

• A red filter absorbs all wavelengths of light other than those in the red range of the spectrum.
• This means only red light is transmitted through the filter.

Question 31

What determines the colour of an opaque object?

Answer 31

• Different objects reflect different wavelengths of lights by different amounts.
• The wavelengths that are most strongly reflected determine the colour.

Question 32

What happens to the wavelengths of light that aren’t reflected by an opaque object?

Answer 32

Any wavelengths that aren’t reflected are absorbed by the object.

Question 33

What colour does an object appear if all wavelengths are reflected by equal amounts?

Answer 33

White.

Question 34

What colour does an object appear if all wavelengths are absorbed?

Answer 34

Black.