P8: Electromagnetic Waves

Question 1

Electromagnetic Spectrum

Answer 1

Smallest - Largest:
Gamma
X-ray
Ultraviolet
Visible
Infrared
Micro
Radio

Question 2

Units of electromagnetic wave measurement from smallest to largest

Answer 2

Picometre
Nanometre
Millimetre
Kilometre

Question 3

How fast do electromagnetic waves travel in a vacuum?

Answer 3

300 million m/s

Question 4

White Light

Answer 4

Light from ordinary lamps and the sun

Question 5

The hotter an object is…

Answer 5

… The more infrared radiation it emits.

Question 6

How does infrared radiation affect the body?

Answer 6

It can damage or kill skin cells by heating them up.

Question 7

Optical fibres

Answer 7

The glass fibre used to send light signals along.

Uses infrared radiation.

Question 8

4 uses of infrared radiation

Answer 8

Optical fibres
remote control handsets
infrared scanners
infrared handsets

Question 9

The shorter the length of radio waves:

Answer 9

The more information they can carry.
The shorter their range.
The less they spread out.

Question 10

What are microwaves used for?

Answer 10

Satellite phones
TV links
Satellite TV
(Can travel between satellites, don’t spread out much so the signal doesn’t weaken as much.)

Question 11

What are radio waves

Answer 11

TV broadcasting
(Can carry more information than longer radio waves)

Question 12

What are radio waves >1m used for?

Answer 12

Local Radio Stations

Have limited range

Question 13

What are radio waves >100m used for?

Answer 13

National and International Radio Stations

Very large range

Question 14

What do electromagnetic waves carry?

Answer 14

Information

Question 15

What effect does UV radiation have?

Answer 15

It is harmful to human eyes and can cause blindness.

Question 16

What produces gamma rays?

Answer 16

Radioactive substances when unstable nuclei release energy.

Question 17

What produces x rays?

Answer 17

When particles moving at high speeds are stopped.

Question 18

Which are more penetrative: X or Gamma rays?

Answer 18

Gamma, they have shorter wavelengths.

Question 19

Applications of X-Rays

Answer 19

X- Rays

To detect internal cracks in metal

Question 20

3 Uses of Gamma Radiation

Answer 20

> Killing bacteria in food
Sterilising surgical equipment
Killing cancer cells.

Question 21

Safety concern of X-Ray and Gamma

Answer 21

Causes ionisation, which can result in cell mutation and death.

Question 22

How an X-Ray works

Answer 22

1. X-Rays from an X-Ray tube are directed at the patient. A lightproof cassette is placed in the other side of the patient.
2. X-Rays pass through soft tissue, but are absorbed by bones, teeth and metal.
3. Where the X-Rays reach the flat-panel detector inside the lightproof cassette it turns darker and creates a clear impression of the bones etc.

Question 23

How to get an X-Ray of an organ.

Answer 23

Give the patient a contrast medium that absorbs x-rays before their scan.

Question 24

Flat Panel Detector.

Answer 24

A small screen that contains a CCD (charge coupled detector), which converts X-Rays to light. The light creates electronic signals which are sent to a computer.

Question 25

CT scanner

Answer 25

Uses X-rays to produce a digital image of any cross section in the body or a three-dimensional image of the body.