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Give three uses of X-rays in medicine.
Kill cancer cells, x ray images and CT scans.
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How does a CT work?
X rays are shot through the body at different angles and detected by detectors on opposite sides, the computer then interprets the signals to form a 2 dimensional slice.
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Give two precautions radiographers take to minimise radiation doses.
Wear lead aprons or stand behind lead screen.
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What is an ultra sound?
Sound above 20,000Hz.
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What happens to an ultra sound when it hits a new medium?
Some of the wave is reflected of the boundary (partially reflected).
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How can you work out the distance between each boundary?
s = v x t (Distance = speed x time)
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Give two uses of ultra sounds.
Pre-natal scanning, breaking down kidney stones.
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what are the two types of lenses?
Convex (converging) and concave (diverging).
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What is the axis of a lens?
The line going through the middle.
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how do you draw a ray diagram for a convex lens (converging)?
first draw straight line from to of object to the to top of lens then top of object to middle of lens, the both lines go through the principal focus.
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How do you draw a ray diagram for a concave lens (diverging)?
Draw line from top of object to top of lens, top of object to middle of lens, top one goes up parallel to the principal focus and middle one goes straight,
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What three ways would you describe a image?
inverted/right way up, size and real of virtual.
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What is a virtual image?
When the rays are diverging so the light from the object appears to be coming from somewhere else.
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What kind of lenses are used in magnifying glasses?
Convex (converging)
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What are the 6 main parts of the eye?
retina, pupil, cornea, iris, ciliary muscles, lens.
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What lens would you use to fix short and long sight?
Short sight is diverging( concave) and long sight is converging (convex)
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Give one way total internal reflection is used.
Optical fibres.
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What is a moment?
The turning effect of a force.
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How do pivots work?
You increase the distance (make the spanner longer) and it increases the moment because Force x distance.
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What is the centre of mass?
the point where all the mass seems be concentrated.
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What two things made an object more stable?
Low centre of mass and wide bases
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What happens if an objects centre of mass lies outside the base of the object.
It will fall over.
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How do hydraulics work?
Small surface area pushes the liquid down and then a piston with a large surface area will be pushed up with a bigger force due to pressure x area = force,
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Pressure at first piston = ? and why?
Pressure at second piston because pressure in a liquid is transmitted equally in all directions.
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Why is an objects velocity always changing when going in a circle?
direction is always changing so velocity is.
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Which way does the centripetal force act?
towards the centre of the circle.
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What three things effect centripetal force?
Mass, Speed and the radius of the circle.
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What is a magnetic field?
A region where magnetic materials and also current carrying wires experience a force.
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What is meant by magnetically soft?
They magnetise and demagnetise easily.
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What is an electromagnet?
A magnetic field that can be turned on or off with an electric current.
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Give one example of an electro magnet.
Some kind of cranes.
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what is the motor effect?
The force which acts on a current-carrying wire in a magnetic field.
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What do each of the fingers represent in Fleming's left hand rule?
thuMb is Motion, First finger is Field and seCond is currect.
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Which way does a magnetic field go?
North to South!
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What makes the split ring communicator a clever idea?
good way of swapping the contacts every half term to keep the motor turning the same way.
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What is electromagnetic induction?
The creation of a potential difference across a conductor which is experiencing a change in magnetic field.
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Give two ways the potential difference/current can be reversed.
Move the magnet the opposite direction and reverse the polarity.
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What are the three key components of a transformer?
Primary coil, secondary coil and the iron core.
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In a step up transformer, does it have more coils on the secondary or the primary coil?
Secondary coil.
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Why do you need AC in a transformer?
the field in the iron core is constantly changing direction which induces electromagnetic induction of a potential difference.
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Vp (p.d acorss primary) Ip (current in primary) = ?
Vs (p.d across secondary) Is (current in secondary).
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What the difference between switch mode transformers and traditional transformers?
switch mode are smaller lighter, work at higher frequencies, more efficient and no load.
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give on example of where a switch mode transformer is used.
Laptop/mobile chargers.
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Other cards in this set

Card 2

Front

How does a CT work?

Back

X rays are shot through the body at different angles and detected by detectors on opposite sides, the computer then interprets the signals to form a 2 dimensional slice.

Card 3

Front

Give two precautions radiographers take to minimise radiation doses.

Back

Preview of the front of card 3

Card 4

Front

What is an ultra sound?

Back

Preview of the front of card 4

Card 5

Front

What happens to an ultra sound when it hits a new medium?

Back

Preview of the front of card 5
View more cards

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