Electromagnetic Waves

Question 1

What are electromagnetic waves made up of?

Answer 1

Oscillating electric and magnetic fields, they oscillate perpendicularly to the direction of propagation of the electromagnetic wave

Question 2

T/F Do electromagnetic waves carry charges

Answer 2

They do not carry electric charges

Question 3

Describe how to find speed of electromagnetic wave in medium

Answer 3

• v = fλ where v is speed, f is frequency and λ is wavelength
• speed of em wave in vacuum is 3.0*10^8

Question 4

State electromagnetic wave with longest wavelength

Answer 4

Radio waves

Question 5

State order of electromagnetic waves from lowest frequency to highest

Answer 5

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

Question 6

What are uses of radio waves

Answer 6

• Television and radio communication
• Radio telescopes for radio astronomy to study radio frequencies from outer space

Question 7

What are uses of microwaves

Answer 7

• Microwave oven
• Wi-Fi signals
• Mobile phone communication
• Global Positioning System and radar

Question 8

What are hazards of microwaves

Answer 8

Heating effect

Question 9

What are uses of infrared radiation

Answer 9

• Remote control
• Intruder alarm
• Thermal imaging
• Camera auto-focusing
• Infrared thermometer

Question 10

What are the uses of visible light

Answer 10

• Photography
• Optical fibres in medicine and telecommunication

Question 11

What are the uses of ultraviolet radiation

Answer 11

• Sterilisation of medical equipment
• Disinfection of water in water treatment plants
• Sunbed for artificial tanning
• Counterfeit bank notes checking

Question 12

What are hazards of ultraviolet radiation

Answer 12

Prolonged exposure can lead to sunburns, premature aging and increased risk of skin cancer
UV radiation can be ionising

Question 13

What are uses of X-rays

Answer 13

• Scan for manufacturing defects in metal parts
• Scan luggage for prohibited items at airports

Question 14

What are uses of gamma rays

Answer 14

• Gamma imaging to detect cancer
• Radiation therapy to treat cancer
• Sterilisation of medical equipment and food

Question 15

What are the hazards of gamma rays

Answer 15

Ionising radiation
Exposure can damage biological molecules, living cells and tissues, leading to cell death, mutations and abnormal cell division
May cause cancers and deformities to developing foetus