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Physics Paper 2 > Topic 6 Em Waves And Rheur Uses > Flashcards

Topic 6 Em Waves And Rheur Uses Flashcards

1
Q

What are microwaves used by

A

Satellite

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2
Q

What does communication to and from satellites use

A

Microwave which can easily pass through the earths watery atmosphere

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3
Q

For satellite TV where is the signal from the transmitter transmitted through

A

Through space

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4
Q

What picks up the signals

A

Satellite receiver dish opting thousands of kilometres above earth satellite transmits a signal back to earth in a different direction

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5
Q

Where is the signal from the satellite dish in space received

A

By satellite dish on the ground there is a slight time delay between single being sent and received because of the long distance the signal has a to travel

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6
Q

What are the microwave is absorbed by in microwave ovens

A

Water molecules in the food

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7
Q

The microwave penetrate up to a few centimetres into the food before doing what

A

Being absorbed and transferring energy that they’re carrying to the water molecules in the food cause in the water to heat up

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8
Q

What are the water molecules do with the energy

A

Transfer this energy to the rest of the molecules in the food by heating

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9
Q

What can infrared radiation be used for

A

To detect infrared or monitor temperature on infrared cameras

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10
Q

What is infrared radiation given off by

A

Hot objects

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11
Q

The hotter the object the

A

The more infrared radiation is given out

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12
Q

What can infrared cameras be used for

A

Detect the IR radiation and turns it into an electrical signal which is displayed on the screen as a picture

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13
Q

The hotter of the object is

A

The brighter it appears on the camera

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14
Q

What does absorbing infrared radiation cause

A

Objects to get hotter

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15
Q

What happens to the temperature of food as it absorbs infrared radiation

A

It increases

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16
Q

What do electric heaters contain

A

How long piece of wire that heats up when I current flows through it

17
Q

What does the wires in electric heaters omit

A

Lots of infrared radiation
And a little visible light (the wire glows)

18
Q

What is the emitted radiation absorbed by

A

The objects on the air in the room

19
Q

What is energy transferred from the Ir waves to

A

The thermal energy stores of objects causing the temperature in to increase

20
Q

What are optical fibres

A

Thing glass or plastic fibres that carry data (from telephones or computers) over long distances as pulses of visible light

21
Q

How do optical fibres work

A

Because of reflection
The light rays are bounced back and forth until they reach the end of the fibre

22
Q

What em wave are used in optical fibres

A

Visible light

23
Q

What happens to the light as it travels along on the fibre

A

It isn’t easily absorbed or scattered

24
Q

What is fluorescence

A

A property of certain chemicals where uv radiation is absorbed and them visible light is emitted

25
Q

What do fluorescent lights generate

A

UV radiation which is absorbed and re emitted as visible light by a laye of a compound called a phosphor on the inside of a bulb
They are energy efficient so they’re good to use when light is needed for long periods

26
Q

Security pens can be used to mark property with your name and what happens under uv light

A

The ink will glow fluorescent but otherwise it is invisible
This can help identify property if it is stolen

27
Q

What can exposure to UV from the sun give u

A

A suntan

28
Q

What do uv lamps give people

A

An artificial sun tan

29
Q

Why can over exposure to uv be bad

A

Cause sun burn or skin cancer

30
Q

What do radiographers in hospitals do

A

Take X-ray photographs of people to see if they have broken bones

31
Q

How can X-rays give u an image

A

Pass easily through flesh but not easily through denser materials like metal or bone
So it is the amount of radiation absorbed or not absorbed that gives the image

32
Q

How do radiographers use x rays and gamma rays to treat people with cancer

A

Through radiotherapy
High doses of these rays kill all living cells so are directed towards the cancer cells to avoid killing to many normal healthy cells

33
Q

How can gamma rays be used as a medical tracer

A

Gamma emitting source is injected into the patient and its progress is followed around the body
Gamma radiation is well suited to this because it can pass our through the body to be detected

34
Q

What do radiographers wear to protect themselfs from exposure

A

Lead aprons and stand behind lead screen or leave room

Physics Paper 2 (47 decks)

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