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22 Cards in this Set
- Front
- Back
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a) What spectrum are x-rays part of?
b) How big is the wavelength of an x-ray?
c) List 3 properties of x-rays?
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a) The electromagnetic spectrum b) About the same size as the diameter of an atom c) Absorbed by hard tissue, transmitted by healthy tissue, affects photographic film in the same way as light, ionising |
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a) What is a CCD?
b) What are CT scanners used for?
c) How do x-rays damage living tissue? |
a) Charge-coupled device, form electronic images of x-rays b) To produce digital images of a cross section of the body c) They cause ionisation |
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a) What is another use of x-rays?
b) What frequency can the human ear detect?
c) What are ultrasound waves? |
a) Treating cancerous tumours near the body surface b) 20 Hz - 20 000 Hz c) Sound waves with frequency above 20 000 Hz |
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a) How do ultrasounds work?
b) What are the medical uses of ultrasounds?
c) What is refraction? |
a) Ultrasound waves are partially reflected at a boundary between two tissues with different densities (s = v x t) b) Scanning and destroying kidney stones c) The change of direction of light as it passes from one transparent substance to another |
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a) What is the refractive index of a substance?
b) What is the critical angle?
c) What is total internal reflection? |
a) How much a substance can refract a light ray (n = sini / sinr) b) The angle of incidence of a light ray in a transparent substance which produces reflection along the boundary c) When the angle of incidence is greater than the critical angle |
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a) What is an endoscope?
b) What is a converging lens?
c) What is a diverging lens? |
a) A device used to see directly inside the body using bundles of optical fibres b) It focuses parallel rays to a point called the principal focus c) It makes parallel rays spread out as if they come from a point called the principal focus |
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a) When are virtual images formed?
b) How do you calculate magnification?
c) What are ray diagrams used for? |
a) By diverging lenses, and by a converging lens if the object is nearer to the lens than the principal focus b) Magnification = image height/object height c) To find the position and nature of an image formed by a lens |
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a) Is an image formed by a camera real or virtual?
b) What is the function of the; 1) cornea 2) eye lens 3) retina 4) iris 5) pupil 6) ciliary muscles 7) suspensory ligaments |
a) A camera uses a converging lens to form a real image of an object b) 1) protective layer, focuses light onto retina 2) focuses light onto retina 3) light sensitive cells inside the eye 4) controls amount of light entering eye 5) light enters through the pupil 6) change the thickness of the eye lens 7) attaches lens to ciliary muslces |
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a) What is the normal range of vision for humans?
b) How do you calculate the power of the lens?
c) What is short-sighted and how is it corrected? |
a) From the near point - 25 cm - to the far point - infinity. b) P = 1 / f c) Distant objects are blurry, eyeball is too long or eye lens is too powerful, corrected using a diverging lens |
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a) What is long-sighted and how is it corrected?
b) In what circumstances can a lens be made flatter and thinner?
c) What is a moment? |
a) Close objects are blurry, eyeball is too short or eye lens is too weak, corrected using a converging lens b) the greater the refractive index of the material of the lens, the thinner it can be c) The measure of the turning effect of the force on an object |
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a) How do you calculate the moment of a force?
b) How do moments of forces relate to levers?
c) What is the centre of mass of an object? |
a) M = F x d b) The increase the moment of a force on a lever, either increase the force, or increase the distance c) The point where an objects mass can thought to be concentrated |
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a) How can you calculate the centre of mass of an object?
b) How can we calculate the force needed to stop an object turning?
c) How can we increase stability? |
a) When a suspended object is in equilibrium, its centre of mass is directly beneath the point of suspension, along the axis of symmetry b) Sum of anticlockwise moments about a point = sum of clockwise moments about a point c) By making the base as wide as possible and the centre of mass as low as possible |
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a) When will an object tend to topple?
b) What is the resultant moment of a toppling object?
c) How do we calculate pressure? |
a) When the line of action of its weight is outside its base b) An object topples over if the resultant moment about its point of turning is not zero c) P = F / A (A = cross-sectional area at right angles to the direction of the force in metres) |
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a) What properties of liquids make them useful in hydraulic systems?
b) How does a hydraulic system work?
c) Define centripetal acceleration |
a) They are virtually incompressible b) A hydraulic system uses the pressure in a fluid to exert a force. The use of different cross sectional areas on the effort and load sides acts as a force multiplier c) The acceleration towards the centre of the circle of an object that is moving round the circle |
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a) What factors affect centripetal force?
b) What are the components of a simple pendulum?
c) How do we measure the time period of a pendulum? |
a) Mass, speed and the radius of the circle b) A suspended mass (called a bob), and string c) We can measure the average time for 20 oscillations and divide the timing by 20 |
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a) What does the time period of a simple pendulum depend on?
b) Why would a swing come to rest if not repeatedly pushed?
c) What does an electromagnet consist of? |
a) Only on the length of the pendulum b) Friction and air resistance will stop the oscillations c) A coil of insulated wire wrapped around an iron core |
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a) What are some uses of electromagnets?
b) What is a magnetic field?
c) When is the force of the motor effect at its maximum? |
a) Scrapyard cranes, circuit breakers, electric bells and relays b) The region around the magnet in which a piece of iron or steel would be attracted to it c) When the wire is perpendicular to the magnetic field |
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a) How can you increase the size of the magnetic field of an electromagnet?
b) How can you reverse the direction of the force?
c) What is Flemmings left-hand rule? |
a) Increase the current or strength of the magnetic field b) If either the direction of the current or the magnetic field is reversed c) Used to determine the direction of force; first finger field, second finger current, thumb movement |
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a) How does a simple electric motor work?
b) What is electromagnetic induction?
c) How can you increase the size of the potential difference? |
a) An electric motor has a coil which turns when a current is passed through it. The split-ring commutator reverses the direction of the current around the coil every half-turn b) The process of creating a potential difference using a magnetic field c) Increase the current, add a core, increase the turns on the coil |
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a) What are the two types of transformer?
b) Why do transformers need a.c. supply?
c) When do you use what type of core? |
a) Step-up and step-down b) A changing magnetic field is necessary to induce a.c. in the secondary coil c) A transformer has an iron core, unless is it a switch mode transformer, which has a ferrite core |
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a) What are the benefits of a switch mode transformer?
b) How can you calculate how much a voltage has been stepped up or stepped down?
c) Why is a transformer used to step up p.d. at power stations? |
a) lighter, smaller, uses very little power when there is no device connected across its output terminals b) Vp / Vs = Np / Ns c)Higher p.d. means less energy wasted through heat transfer |
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a) What equation is correct for a 100% efficient transformer? |
a) Vp x Ip = Vs x Is |
