Electromagnetic spectrum

Question 1

List the order of the electromagnetic spectrum from long wavelength to short wave length

Answer 1

Radio waves
Micro waves
Infra red
Visible light
Ultra violet light
X-ray
Gamma ray

Question 2

How is the order of the electromagnetic spectrum determined

Answer 2

Decreasing wavelength and increasing frequency from Radio to Gamma

Question 3

How is body tempertaure kept constant

Answer 3

It needs to radiate the same average power as it absorbs

Question 4

What are radio waves used for

Answer 4

broadcasting, communications and satellite transmissions

Question 5

What are micro waves used for

Answer 5

cooking, communications and satellite transmissions

Question 6

What is infra red used for

Answer 6

cooking, thermal imaging, short range communications, optical fibres, television ​remote controls and security systems

Question 7

What is visible light used for

Answer 7

vision, photography and illumination

Question 8

What is ultraviolet light used for

Answer 8

security marking, fluorescent lamps, detecting forged bank notes and disinfecting ​water

Question 9

What are x-rays used for

Answer 9

observing the internal structure of objects, airport security scanners and medical X-​rays

Question 10

What are gamma rays used for

Answer 10

sterilising food and medical equipment, and the detection of cancer and its ​treatment

Question 11

How can micro waves be dangerous

Answer 11

Internal heating of body cells

Question 12

How is infra red dangerous

Answer 12

Skin burns from an intense source

Question 13

How is ultraviolet dangerous

Answer 13

damage to surface cells and eyes, leading to skin cancer and eye conditions

Question 14

How are x-rays and gamma rays harmful

Answer 14

mutation or damage to cells in the body
Gamma- a big dose leads to dna breakdown-radiation sickness
X-ray- cells are altered and produce a cancerous tumour

Question 15

How can radio waves be produced

Answer 15

Oscillations in electrical circuits
The higher the frequency of radio wave, the faster the oscillations of the electrons.
They are received by being absorbed by the electrons in a wire (eg aerial), which then start to oscillate.

Question 16

Changes in an atoms nuclei can…

Answer 16

a) generate radiations over a wide frequency range
​b) be caused by absorption of a range of radiations

Question 17

How does danger increase within the EM spectrum

Answer 17

Danger increases with increasing frequency

Question 18

What happens to the speed of the EM waves in a vacuum

Answer 18

The speed stays the same but their frequencies are different

Question 19

What 3 groups of EM waves ionise

Answer 19

U-V, X-rays, Gamma rays

Question 20

What is the speed at which EM waves travel through a vacuum at

Answer 20

3 x 10^8 m/s

Question 21

Explain how radio waves can be transmitted around the curvature of the Earth

Answer 21

The atmosphere gets thinner as the altitude increases. Therefore radio waves refract as they rise. Unless pointed straight up, this causes them to change direction until they reach the CRITICAL ANGLE with the atmosphere (at the ionosphere), at which point they reflect back down (total internal reflection).

Question 22

How is IR linked to the greenhouse gas effect

Answer 22

Ideally IR power absorbed by Earth = IR power radiated by Earth (earths temp stays constant)
Because the rate of IR ABSORBED is GREATER THAN the IR EMITTED, the earths surface temperature will rise until it is sufficiently hot for the rates to be equal again and stabilise at that new higher temperature
This is global warming

Question 23

How and where are gamma rays produced

Answer 23

By an annihilation of a positron when it comes into contact with an electron - gamma rays are released
Gamma rays are produced in the nucleus