Electromagnetic Spectrum

Question 1

Who discovered infrared waves in 1800 and how did he do it?

Answer 1

William Herschel. He was investigating the temperatures of the visible spectrum and found that there were hotter temperatures beyond red.

Question 2

Who discovered ultraviolet in 1801 and how did he do it?

Answer 2

John Ritter. While experimenting with silver chloride used in photography, he found that the rate of reaction was highest beyond violet

Question 3

Which end of the visible light spectrum has the longest wavelength?

Answer 3

Infrared light has longer wavelengths than ultraviolet light

Question 4

How are ultraviolet waves harmful?

Answer 4

They will damage skin cells and eyes. The most common form is sunburn but over exposure can cause skin cancer

Question 5

Name the EM waves in of decreasing wavelength.

Answer 5

radio waves, microwaves, infrared radiation, visible light, ultraviolet, x-rays, gamma rays

Question 6

How are radio waves produced? and what are the used for?

Answer 6

They are produced and detected by aerials. They are used to broadcast television and radio programmes and are also used by emergency services for communication

Question 7

What are microwaves used for?

Answer 7

They are used to cook food in a microwave oven and they are also used for mobile-phone communication

Question 8

What are infrared waves used for?

Answer 8

Infrared waves are used in cooking and are in cameras to find bodies under rubble, short-range communication

Question 9

What is visible light used for?

Answer 9

It is used in photography and in lighting our homes and streets

Question 10

How do UV lamps work?

Answer 10

They produce UV light when mercury vapour conducts electricity

Question 11

What is UV used for?

Answer 11

It can be used to view security markings on bank notes and it is also used to steralise water

Question 12

How are x-rays produced and what are they used for?

Answer 12

They are produced when fast-moving electrons hit a metal plate. They can be used to detect an objects internal structure, medical x-rays to detect the condition of bones and teeth, to detect unwanted pieces of metal in machinery and they are also used in airport security scanners.

Question 13

How are gamma rays produced and what are they used for?

Answer 13

They are produced by radioactive materials. They can be used to steralise food and medical equipment. They can also be used to detect and treat cancer.

Question 14

Are radio waves harmful and if so how?

Answer 14

They are safe because they do not produce ionisation

Question 15

Are microwaves harmful and if so how?

Answer 15

Yes they can cause internal heating of the body cells

Question 16

Is Infrared radiation harmful and if so how?

Answer 16

Yes it can cause skin burns

Question 17

Is visible light harmful and if so how?

Answer 17

Yes, intense light can cause permanent damage to the retine

Question 18

Is ultraviolet harmful and if so how?

Answer 18

Yes, intense ultraviolet damages skin cells, triggers skin cancer, can cause eye condition e.g cataracts, can destroy protein in the eye lens

Question 19

Are x-rays and gamma rays harmful and if so how?

Answer 19

Yes, they can damage the DNA of cells, mutate cells and can trigger cancer

Question 20

Define RADIOACTIVITY

Answer 20

It is when atoms have unstable nuclei, which then break down releasing energy in the form of alpha or beta particles or gamma rays

Question 21

When were x-rays and radioactivity discovered?

Answer 21

At the end of the 19th century

Question 22

Define IONISATION

Answer 22

It is when radiation transfer some of their energy to the atoms of the material they are passing through. When this happens, electrons get knocked off the atom to for a positive ion

Question 23

How does a geiger-muller tube work?

Answer 23

When alpha or beta particles enter the tube, it ionises the gas inside of it. This produces a pulse of electrical charge, which is detected by the counter attached to the GM tube. Each click or counts represents one particle being detected.