Electromagnetic Spectrum

Question 0

As wavelength increases, what happens to the frequency?

Answer 0

Frequency decreases

Question 1

Why do digital signals give better quality reception?

Answer 1

The noise is more easily removed (through regeneration)

Question 2

Speed of EM waves

Answer 2

All parts of the EM spectrum waves travel at the same speed in free space
This speed is the speed of light (300 000 000 m/s)

Question 3

Uses of radio waves 3

Answer 3

Broadcasting & communications

Satellite transmissions

Question 4

Uses of microwaves

Answer 4

Mobile phones, satellite transmission & cooking

Question 5

Infrared uses 3

Answer 5

Heaters, night vision & remote controls

Question 6

Visible light uses 2

Answer 6

Optical fibres & photography

Question 7

UV uses 4

Answer 7

Fluorescent lamps eg tanning machines, disinfecting water, security markings eg for Chas king banknotes

Question 8

X ray uses

Answer 8

Observing the interval structure of objects & materials(not just medical applications)

Question 9

Gamma rays uses

Answer 9

Sterilising medical equipment, food & radiotherapy

Question 10

Effects of over exposure to microwaves

Answer 10

Internal heating of body tissue

Question 11

Effects of over exposure to infrared

Answer 11

Surface burns to skin

Question 12

Effects of over exposure to UV

Answer 12

Damage to skin cells at the surface & to retinal damage

Question 13

Effects of over exposure to X rays & gamma rays

Answer 13

Killing & mutation of cells

Cancer

Question 14

What happens when electromagnetic radiation from the sun arrives at the earths atmosphere?

Answer 14

Some reflected
Some transmitted to earths surface
Some absorbed by atmosphere

Question 15

Types of electromagnetic radiation that arrive at the earths surface

Answer 15

High energy infrared
Visible light
Low energy ultraviolet

Question 16

Properties of radio waves & microwaves 3

Answer 16

• They are reflected by metal surfaces
• They heat materials if they can make particles in the material vibrate
• The amount of heating depends on the power of the radiation & the time that the material is exposed to the radiation

Question 17

How are people exposed to microwave radiation through their phones? 2

Answer 17

To the head from the aerial in the phone

To the body from transmitters in base station masts

Question 18

Radio waves emitted & detected

Answer 18

Emitted by a transmitter & detected by an aerial

Question 19

Why does food cook more quickly in a microwave

Answer 19

Water molecules in the food absorb the microwaves and become very hot
Food therefore cooks throughout rather than just from the outside

Question 20

Give one confirmation that microwaves can pass through glass, brick and so on

Answer 20

We are able to use mobile phones almost anywhere at work or home

Question 21

How do microwave ovens prevent human body tissue from also being heated

Answer 21

They have metal screens that reflect microwaves and keep them inside the oven

Question 22

Why don’t mobile phones cook your brain

Answer 22

The microwaves used transmit much less energy than those used in a microwave oven

Question 23

Why can we use x rays to check a patients bones

Answer 23

X rays pass easily through soft body tissue but cannot pass through bones

Question 24

Which feature or characteristic of one electromagnetic wave makes it different from another electromagnetic wave

Answer 24

Its frequency

Question 25

Why do both digital and analogue signals have to be amplified along their route

Answer 25

They weaken as they travel

Question 26

What is thermal (infra red) radiation?

Answer 26

The transfer of energy by electromagnetic waves