Chapter 5 - EM Waves

Question 1

What is the EM waves our eyes detect?

Answer 1

Visible

Question 2

Name the 7 parts of the EM spectrum in order from longest to shortest waves

Answer 2

Radio waves, microwaves, infra red rays, visible, ultraviolet waves, X rays, gamma rays

Question 3

Which wave has the highest energy and the highest frequency?

Answer 3

Gamma rays

Question 4

Which wave has the lowest frequency and the lowest energy ?

Answer 4

Radio waves

Question 5

What size does visible light rays range? What are the colours of each end?

Answer 5

390 nm, violet

698nm, red

Question 6

What are the uses of infra red?

Answer 6

Cooking, remotes, fibre optics, communication

Question 7

What are the uses of gamma?

Answer 7

Sterilising food and equipment, gamma knifes / radiotherapy

Question 8

What are radio waves used for ?

Answer 8

Communicating

Question 9

What are microwaves used for?

Answer 9

Communicating and cooking

Question 10

What are x rays used for?

Answer 10

Security scans, imaging hard tissue

Question 11

How large are radio waves?

Answer 11

100km to 1m

Question 12

How large are microwaves?

Answer 12

1m to 1mm

Question 13

How large are infra red rays?

Answer 13

1mm to 698 nm

Question 14

Can EM waves travel through a vacuum? How do we know this?

Answer 14

Yes, we can feel the UV rays from the sun and see visible light of stars

Question 15

What rays are absorbed by the atmosphere?

Answer 15

Gamma , x rays, some UV, some Radio and some microwaves

Question 16

How large are gamma rays?

Answer 16

100 pm , picometres, 1 trillionth of a metre

Question 17

Which wave is getting trapped in our atmosphere more? What is causing this?

Answer 17

Infra red, the increase of greenhouse gases is causing this and this is causing the Earth to heat up

Question 18

Which is the least dangerous out of all the EM waves? Which is the most dangerous?

Answer 18

Radio is the least dangerous, gamma is the most

Question 19

How is UV rays dangerous?

Answer 19

It can cause skin cancers by making mutations in the cells

Question 20

How’s gamma dangerous?

Answer 20

It’s radioactive, can kill cells or cause very bad mutations in them

Question 21

How is visible light dangerous?

Answer 21

It can blind you if you have to much at once, like looking into the sun or a layer

Question 22

How are x rays dangerous?

Answer 22

Damages living tissue, general cancer causer so there is a cap on x rays you can have a year

Question 23

How is infra red dangerous?

Answer 23

Can cause skin burns, heating of body tissues , break up of cells

Question 24

How are microwaves dangerous?

Answer 24

They can heat from the inside, mobile phone signals could cause very dangerous brain cancers (not certain yet)

Question 25

What do filters do to visible light?

Answer 25

Only allow a certain colour through, or whatever makes up that colour

Question 26

What colour would green appear under a yellow filter? What about blue under a yellow filter?

Answer 26

Green would still appear green through yellow filter because yellow is made up of 2 out of 3 primary colours red and green so the yellow filter is still letting green through. Blue would appear black under a yellow filter because yellow isn’t letting any blue through so the object doesn’t reflect any colour

Question 27

What are the 3 primary colours (in PHYSICS not art, hint: think about the eye)?

Answer 27

The colours our eyes detect which make up all the other colours our eyes detect, red, green and blue

Question 28

Under a blue filter what does a white object appear as? Is this the same for other colours? Why?

Answer 28

It appears blue, under any colour filter white appears the same colour as that filter. This is because white absorbs and reflects all colours so if it is only absorbing one colour, in this case blue, then it is only able to reflect that colour too.