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):

radiowaves uses

transmit television and radio programmes


radiowaves dangers

large doses cause cancer and leukuemia


microwave uses

heat up food and use in mobile phones


microwaves dangers

internal heating of body tissue


infared uses

remote controls and recorders


infared dangers

heat causes skin cancer and burns


visible light uses

light up environment


visible light dangers

blinding of eyes and thermal heat if concentrated


ultraviolet light uses

killing microbes and makes clothes glow


ultraviolet dangers

severe burns and damage to cells


x ray uses

see inside people and airport security


x ray dangers

damage cells and cause mutations


gamma ray uses

kill cancer cells and radiotherapy


gamma ray dangers

cause genetic mutation


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


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


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


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


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


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