P1 - Electromagnetic Waves

Question 0

What are EM waves?

Answer 0

Electric and magnetic disturbances that transfer energy.

Question 1

What are the parts of the EM spectrum?

Answer 1

• Radio
• Microwave
• IR
• Visible Light
• UV Radiation
• Gamma radiation and X-Rays

Question 2

What is the speed of an EM wave?

Answer 2

300,000,000 ms^1

Question 3

How does the energy of an EM wave change with its frequency?

Answer 3

The higher the frequency, the higher the energy.

Question 4

Which EM waves have the highest energy?

Answer 4

Gamma rays because they have the shortest wavelength.

Question 5

What is white light?

Answer 5

White light contains all the colours of the spectrum.

Question 6

What is IR used for?

Answer 6

Carrying signals from remote devices and inside optical fibres.

Question 7

What are microwaves used for?

Answer 7

Carrying satellite TV programmes and mobile phone calls.

Question 8

What are radio waves used for?

Answer 8

Radio and TV broadcasting, radio comms and mobile phone calls.

Question 9

What are the hazards of light, infrared, micro and radio waves?

Answer 9

Microwaves and radio waves cause internal heating.

IR causes skin burns.

Question 10

Why are microwaves used to beam signals long distances?

Answer 10

Microwaves don’t spread out as much as radio waves.

Question 11

What is the range of radio wave frequencies?

Answer 11

300kHz - 3GHz

Question 12

Give a specific use of radio waves.

Answer 12

Bluetooth allows devices to connect up to ten metres away without cables.

Question 13

Why are different wavelength radio waves used for different purposes?

Answer 13

The wavelength affects:

• how far the wave can travel.
• how much the waves spread.
• how much info. a wave can carry.

Question 14

Which type of wave is used for satellite TV?

Answer 14

Microwaves.

Question 15

What are optical fibres?

Answer 15

Thin, transparent fibres that transmit signals using light and IR.

Question 16

How are radio waves emitted from an aerial?

Answer 16

Alternating voltage through the aerial. The frequency of the radio wave is the same as the wave of alternating voltage.

Question 17

How do aerials receive data?

Answer 17

When the incoming radio waves passes across the aerial, an alternating voltage is produced which is connected to a speaker, producing sound waves.

Question 18

Give two advantages of fibre optic communications.

Answer 18

• More info. can be carried due to the much smaller wavelength.
• More secure because the signal stays within the fibre.

Question 19

What is red shift?

Answer 19

The shift to longer wavelengths of the light from it be use the object is moving away.

Question 20

How does red-shift depend on speed?

Answer 20

The faster a galaxy is moving away, the greater its redshift.

Question 21

What evidence is there of distant galaxies moving away from Earth?

Answer 21

All distant galaxies show redshift. The further away the galaxy is, the greater its redshift.

Question 22

What is the Doppler effect?

Answer 22

The change in observed wavelength due to motion of the source of the wave.

Question 23

Give two examples of the Doppler effect.

Answer 23

A train going past a station (sound).

Redshift (light).

Question 24

What is the namesake of redshift.

Answer 24

The spectrum of light shifts towards the red part of the spectrum, the longer wavelength.

Question 25

What is the opposite of redshift?

Answer 25

Blueshift, squashing of waves towards the blue part of the spectrum.

Question 26

What is the Big Bang Theory of the universe?

Answer 26

The universe started with the Big Bang from a singular point.

Question 27

Why is the universe expanding?

Answer 27

The Big Bang caused everything to move away from the point of rapid expansion.

Question 28

What is cosmic microwave background radiation?

Answer 28

Electromagnetic radiation created after the Big Bang.

Question 29

What evidence is there to support the Big Bang?

Answer 29

CMBR can only be explained by the Big Bang Theory.