EM Waves' Dangers And Uses Flashcards Preview

Physics 2 - Waves And The Electromagnetic Spectrum > EM Waves' Dangers And Uses > Flashcards

Flashcards in EM Waves' Dangers And Uses Deck (20):
1

radiowaves uses

transmit television and radio programmes

2

radiowaves dangers

large doses cause cancer and leukuemia

3

microwave uses

heat up food and use in mobile phones

4

microwaves dangers

internal heating of body tissue

5

infared uses

remote controls and recorders

6

infared dangers

heat causes skin cancer and burns

7

visible light uses

light up environment

8

visible light dangers

blinding of eyes and thermal heat if concentrated

9

ultraviolet light uses

killing microbes and makes clothes glow

10

ultraviolet dangers

severe burns and damage to cells

11

x ray uses

see inside people and airport security

12

x ray dangers

damage cells and cause mutations

13

gamma ray uses

kill cancer cells and radiotherapy

14

gamma ray dangers

cause genetic mutation

15

why dont we need satellites for radiowaves

- 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

16

why do microwaves need satellites

- 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

17

how do infared and microwaves heat up food differently

- 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

18

why do we use radiotowers for phones

- 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

19

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

- 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

20

how do micro wave oven heat up food quickly

- 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