# X-rays

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What do you need to produce x-rays?
A cathode, an anode, an evacuated gas tube and some thermionic emission
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What acts as the cathode? What happens when it is heated?
A filament acts as the cathode and once it is heated it gives more energy to its electrons.
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What happens when the electrons have enough energy from the cathode?
When they have enough energy the electrons 'boil off' which means that they escape.
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What is the process of this called?
It is thermionic emission.
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What is the wire filament (cathode) also known as?
An electron gun
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What happens to the electrons after they have escaped?
They accelerate towards the anode by a potential difference between the anode and the cathode.
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What happens after the electrons accelerate towards the anode?
When the electrons collide with the anode (which is a metal target in this case), some of their kinetic energy is converted into x-rays and thermal energy.
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Why does this happen in an evacuated gas tube?
The glass tube contains a vacuum to prevent the electrons colliding with air particles.
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Why is it important that the electrons don't collide with air particles?
Colliding with air particles would knock the electrons off target and decrease their energy.
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Why is a lead casing placed around the tube?
Lead is put around the tube to absorb some of the x-rays so that they're only aimed at the object in question, e.g. an arm
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What is the beam of electrons produced equivalent to?
An electric current.
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What does the intensity of radiation depend on?
How far away you are from the source - the further away you are, the less effected you are by the radiation.
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What is the inverse square relationship?
If you move twice as far from a source, the same radiation is being spread over four times the area and is therefore being reduced.
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How can the inverse square relationship be shown mathematically?
1/2'2 = 1/4 (1 over 2squared = 1 over 4)
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How does density relate to radiation absorption?
The more dense a material, the more radiation is absorbs.
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What materials are used to absorb x-rays?
Lead and concrete are used to absorb x-rays.
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## Other cards in this set

### Card 2

#### Front

What acts as the cathode? What happens when it is heated?

#### Back

A filament acts as the cathode and once it is heated it gives more energy to its electrons.

### Card 3

#### Front

What happens when the electrons have enough energy from the cathode?

### Card 4

#### Front

What is the process of this called?

### Card 5

#### Front

What is the wire filament (cathode) also known as?