They affect photographic film in the same way as light, they are absorbed by metal and bone and they are transmitted by healthy tissue.
2 of 30
Give a dis-advantage of x-rays.
They are very ionising so they can damage living tissue when they pass through it.
3 of 30
What precautions to radiographers take when using x-rays?
Wearing film badges and lead vests.
4 of 30
Give 2 ways x-rays may be used in hospitals.
To check for fractures in bones and to treat cancerous tumours near the bodys surface.
5 of 30
What is the frequency of ultrasound waves?
Over 20,000 Hz.
6 of 30
How are ultrasound images produced by electronic systems?
An ultrasound wave is sent out, when it meets a boundary between two different materials part of the wave is reflected. The wave travels back through the material to a detector which can be used to calculate how far away the boundary is.
7 of 30
Why are ultrasound scans safer than an x-ray?
Ultrasound is non-ionising.
8 of 30
How is ultrasound used in hospitals?
Scanning for unborn babies, scanning soft tissue such as the eye and in therapy such as destroying kidney stones.
9 of 30
What is refraction?
Refraction is the change of direction of light as it passes from one transparent substance into another.
10 of 30
Why does refraction take place?
Because waves change speed when they cross a boundary. The change in speed causes a change in direction unless the waves are travelling along the normal.
11 of 30
What is the refractive index of a substance?
The refractive index of a substance is a measure of how much the substance can refract a light ray.
12 of 30
Which way does a light ray change direction when it crosses from glass to air?
It refracts away from the normal.
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What happens when the angle of incidence is increased?
The angle of refraction increases until the refracted ray emerges along the boundary.
14 of 30
What is the critical angle?
The critical angle is the angle of incidence of a light ray in a transparent substance which produces refraction along the boundary.
15 of 30
When does total internal reflection occur?
When the angle of incidence of a light ray in a transparent substance is greater than the critical angle.
16 of 30
How does an edoscope work?
It contains bundles of optical fibres which are very thin flexible glass fibres. Visible light can be sent along then by total internal reflection.
17 of 30
What is an endoscope used for in hospitals?
Used to look inside the body without cutting it open or during keyhole surgery.
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What is a converging lens?
A converging lens is convex, when parallel rays of light pass through it they converge to a point called the principal focus. It produces a real image if the object is further away than the principal focus and a virtual image if the object is nearer.
19 of 30
What is a diverging lens?
A diverging lens is concave, when parallel rays of light pass through it they spread out from the principal focus point. It produces a real image.
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How is magnification calculated?
Image height ~ object height
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What is the focal length?
The distance from the centre of the lens to the principal focus.
22 of 30
What lens does a camera use?
Converging to form a real image.
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What happens inside the eye when light enters?
Light enters the eye through the cornea. The cornea and the eye lens focus light on the retina. The iris adjusts the size of the pupil to control the amount of light entering the eye.
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What is the human eyes range of vision?
25cm to infinity.
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What lens does a short sighted person need?
Short sighted eyes can only see close up objects clearly so they need a diverging lens.
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What lens does a long sighted person need?
Long sighted eyes can only see distant objects clearly so they need a converging lens.
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What defect of the eyeball may cause short sight?
The eyeball being too long or the eye lens being too powerful.
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What defect of the eyeball may cause long sight?
The eyeball being too short or the eye lens being too weak.
29 of 30
What is a CT scanner?
A device that uses x-rays to produce a cross section of images through the body.
30 of 30
Other cards in this set
Card 2
Front
Give 3 properties of x-rays.
Back
They affect photographic film in the same way as light, they are absorbed by metal and bone and they are transmitted by healthy tissue.
Card 3
Front
Give a dis-advantage of x-rays.
Back
Card 4
Front
What precautions to radiographers take when using x-rays?
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