Electromagnetic Waves and Dangers of Electromagnetic Waves

Question 1

What are all EM waves?

Answer 1

Transverse waves, that transfer energy from a source to an absorber

Question 2

What would all EM waves do in a vacuum or in the air?

Answer 2

Travel at the same speed

Question 3

How are EM waves grouped?

Answer 3

Based on their wavelength and frequency, with INCREASING frequency and DECREASING wavelength

Question 4

Name some uses of Radio Waves?

Answer 4

Mainly communication e.g radios
- They are used as they can travel long distances
before being absorbed.

Question 5

Name some uses of Microwaves?

Answer 5

1) Communications between satellites

2) Microwave Ovens

Question 6

Why are Microwaves used in Satelite communication?

Answer 6

They can easily pass through the earth’s atmosphere, without being reflected or refracted

Question 7

Why are microwaves used to heat food?

Answer 7

They can heat up the water molecules in water, as the water molecules absorb the energy, it increases the temperature of the food.

Question 8

Name a uses for Infrared EM waves?

Answer 8

• Infrared Cameras - to check for heat loss
• Electrical heaters - when emitted the infrared waves
  energy is easily absorbed by other objects,
  increasing there temp

Question 9

Name some uses of visible light?

Answer 9

Fibre Optics

Question 10

What are optical fibres?

Answer 10

Thin glass or plastic fibre that can carry data over long distances. They work due to reflection as visible light is reflected along the fibre.

Question 11

Why is visible light used in Fibre optics?

Answer 11

Due to visible lights short wavelength, it can carry lots of information.

Question 12

Name some uses for UV waves?

Answer 12

1) Energy efficient lightbulbs
2) Tanning Salons
3) Fluorescent lights

Question 13

Why are UV waves used in energy efficient lightbulbs?

Answer 13

Due to its short wavelengths, it carries more energy than visible light, this energy is then absorbed by the interior surface of the bulb and turned into visible light.

This requires much less energy than a normal light bulb.

Question 14

What are both X-Rays and Gamma Rays used for?

Answer 14

Medical imaging
- X Rays used to visualise broken bones
- Gamma Rays can be used to detect cancer - as they
are very penetrating and can pass through the body
tissue

Question 15

Why are X-Rays used to see bones?

Answer 15

X-Rays are very penetrative (able to make it through human skin and bones) and are then absorbed by the bones so that they can be seen.

Question 16

What are the dangers of Low-Frequency waves?

Answer 16

None, as they don’t transfer much energy and so mostly pass through soft tissue without being absorbed.

Question 17

What is the danger of UV radiation?

Answer 17

Damages surface cells, which can lead to sunburn and further develop into an increased risk of skin cancer

Question 18

What is the danger of X-Rays and Gamma rays?

Answer 18

They are a type of ionising radiation that can cause gene mutation or cell destruction, and cancer.

Question 19

What is done before any of the high-frequency types of radiation are used in medical injuries?

Answer 19

The risks and benefits and measured up.

Question 20

What are radiation doses measured in?

Answer 20

Sieverts (Sv) - is a measure of the risk of harm from the body being exposed to radiation (measured normally in millisieverts 1000 mSv = 1 Sv)

Question 21

What does the radiation dose risk depend on?

Answer 21

The total amount of radiation absorbed AND how harmful it is.

Question 22

Where is Infrared radiation emitted from?

Answer 22

The surface of an object (the hotter the object the more IR radiation is given at a time)

Question 23

How do some colours affect the rate of absorption of IR radiation?

Answer 23

Some colours e.g black are better at absorbing and emitting radiation than white.

Or Matte surfaces are better at absorbing and emitting radiation than a shiny one

Question 24

Objects at a constant temperature are emitting infrared radiation….?

Answer 24

At the same rate as they are absorbing it

Question 25

What happens to an object that is hotter than its surroundings?

Answer 25

It is emitting more IR radiation than it absorbs as it cools down.

Question 26

What happens to an object that is cooler than its surroundings?

Answer 26

They absorb more IR radiation than it emits as it warms up.