EM Waves' Dangers And Uses

Question 1

radiowaves uses

Answer 1

transmit television and radio programmes

Question 2

radiowaves dangers

Answer 2

large doses cause cancer and leukuemia

Question 3

microwave uses

Answer 3

heat up food and use in mobile phones

Question 4

microwaves dangers

Answer 4

internal heating of body tissue

Question 5

infared uses

Answer 5

remote controls and recorders

Question 6

infared dangers

Answer 6

heat causes skin cancer and burns

Question 7

visible light uses

Answer 7

light up environment

Question 8

visible light dangers

Answer 8

blinding of eyes and thermal heat if concentrated

Question 9

ultraviolet light uses

Answer 9

killing microbes and makes clothes glow

Question 10

ultraviolet dangers

Answer 10

severe burns and damage to cells

Question 11

x ray uses

Answer 11

see inside people and airport security

Question 12

x ray dangers

Answer 12

damage cells and cause mutations

Question 13

gamma ray uses

Answer 13

kill cancer cells and radiotherapy

Question 14

gamma ray dangers

Answer 14

cause genetic mutation

Question 15

why dont we need satellites for radiowaves

Answer 15

• because radiowaves are reflected back to earth by the ionosphere
• this is because its frequency is too low so it therefore doesnt have enough power to escape

Question 16

why do microwaves need satellites

Answer 16

• because microwaves penetrate the ionosphere
• so they dont hey bounced back to earth
• this means that we need something to transmit them back which is a satellite

Question 17

how do infared and microwaves heat up food differently

Answer 17

• infared waves heat up the surface of food
• where as microwaves penetrate a few centimeters into the food
• vibrate the water molecules in food, heating it from the inside

Question 18

why do we use radiotowers for phones

Answer 18

• distance from cell phone to tower is a few miles
• so less power is used transmit and receive signals
• long distances add to delay in communication and reduced quality of service

Question 19

with long radio waves, why can radio signals be recieved even though the reciever isnt in the line of sight of the transmitter

Answer 19

• their wavelengths of 1 to 10km can be recieved halfway around the world from where they started
• because long wavelengths tend to bend around the curved surface of the earth

Question 20

how do micro wave oven heat up food quickly

Answer 20

• the microwaves penetrate into the food
• before begin absorbed and and transferring energy they are carrying to the water molecules in the food
• causing the water heat up
• water molecules transfer the energy to the rest of the molecules in the food internally, quickly heating the food