EM Waves

Question 1

What is a EM Waves

Answer 1

Transverse waves that transfer energy as waves from a source to an absorber

Question 2

Why are the EM Waves different?

Answer 2

Same speed but a different frequency and wavelength

Question 3

What are EM waves made out of

Answer 3

Oscillating electric and magnetic fields
Alternating currents are made up of oscillating charges. As the charges oscillate they produce oscillating electric and magnetic fields

Question 4

What is the frequency of waves equal to

Answer 4

Frequency of alternating currents

Question 5

How can you produce radio waves

Answer 5

Using an alternating current in an electrical circuit
The object that charges (electrons) oscillate to create the radio waves is called a transmitter

Question 6

How do radio waves work?

Answer 6

AC is supplied to a transmitter and electrons oscillate and produce EM waves
The emitted radio waves transfer energy to the receiver
The EM waves are absorbed and cause electrons in the receiver to oscillate and AC is produces in the receiver

Question 7

How long are radio waves

Answer 7

Longer than 10 cm wavelength

Question 8

Long waves radio

Answer 8

Wavelength of 1-10km
This is because the long wavelengths diffract (bend) around the curved surface of the Earth. Long-wave radio wavelengths can also diffract around hills, through tunnels ect
This makes it possible for radio waves to be transmitted without a line of sight of the receiver

Question 9

Short Wave radio

Answer 9

Wavelength of 10-100m
This is because they are reflected by the ionosphere (electrically charged layer in the earths atmosphere)

Question 10

Bluetooth

Answer 10

Uses short range radio waves to send data over short distances between devices without wires

Question 11

Medium Waves signals

Answer 11

Can reflect from the ionosphere depending on the atmospheric conditions and the time of day

Question 12

What is the ionosphere

Answer 12

Electrically charged layer in the Earth’s upper atmosphere

Question 13

Microwaves communicate with what and how

Answer 13

Satellites (including satellites including TV signals and satellites phones) using microwaves
For satellite TV the signal from a transmitter is transmitted into space where is it picked up by the satellite receiving dish and transmitted back to earth where it is received by a satellite dish on the ground

Question 14

How do microwaves work (food)

Answer 14

They send waves of energy that penetrate the food by a few centimetres and transfer energy to the water molecules, which causes it to heat up