Physics P3

  • Created by: Matty0127
  • Created on: 08-12-16 19:26
How does a CAT scan work?
A CAT scan uses X-rays to make a detaile picture of part of your body. This scan can be used to create 3D images on a computer.
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How does an ultrasound scanner work?
An ultrasound is pointed at the patient body, it will produce high-frequency sounds waves that are reflected by the features inside a human body.
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How does an endoscope work?
An endoscope allows keywhole surgery, it is build off optical fibres which provide live view of the internal structure in a patient.
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How does an fluoroscope work?
A fluoroscope is used to study moving body structures, continous x-ray beams are passed through the body part which is being examined. The beam is transmited to a TV-like monitor so that the body part and its motion can be seen in detail.
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What are the dissadvantages of a CAT scan?
A CAT scan is expensive, and the patient gets a relatively high dosage of radiation from it, which could result in mutations.
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What are the advantages of a CAT scan?
A Cat scan produces detailed images, that can be used to build up a 3D image on a computer.
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What are the advantages of an ultrasound?
There is virtually no risk in ultrasounds, and it allows real-time image to be viewed.
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What are the advantages of a endoscope?
It provides a direct, real time view of internal body tissue, it also allows keyhole surgery, without the need for major surgery.
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What are the dissadvantages of a endoscope?
An endoscope cant see through tissue.
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Why does distance affect radiation intensity?
The intensity of radiation is the amount of energy arriving per second over an are 1m^2. Energy spread out from a source in all directions. The intensity decreases with distantce becasue the radition is spread over a increasing area.
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What is intensity measure in?
W/m^2
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What is power measured in?
Watts (W)
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What is aread measured in?
m^2
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What does the retina do?
It contains light receptors, which trigger electrical impulses to be sent to the brain when light is detected.
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What does the lens do?
The lens refracts light to focus onto the retina. This is adjusted by changing the thickness and curvature of a lens.
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What does the pupil do?
The pupil allows light to pass throught the eyes.
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What does the cornea do?
A long side the lens, the cornea refracts light by a fixed amount as it enters the eye
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What does the Iris do?
The iris controls how much light enters the pupil, by contracting or relaxing the size of the pupil.
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What do clilary muscles do?
The clilary muscles adjust the shape of the lens - making it more or less curved, to increase or decrease the refraction of light.
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What does the optic nerve do?
The optic nerve carries impulses from the nrain to the retina.
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Is the lens, less curved or more curved when focusing on long distant objects?
Less curved, therfore slimmer.
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Is the lens less, less curved or more curved when focusing on near objects?
More curved, therfore fatter.
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What does far point mean?
Far point is the most distant point the eye can focus, this is infinity.
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What is the near point?
The near point is the closes point on which the eye can focus, this is usually 25cm.
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What does the converging lens do?
The convering lens bends rasy of light toward one another, bringign them at a point.
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What does the diverging lens do?
A diverging lens bends rays of light away from each over.
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What is a different between a diverging lens and a converging lens over than refraction?
The converging lens is thicker in the middle, and the diverging lens is thinner in the middle.
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What does it mean to be long-sighted?
Long-sighted people can focus on distant objects, but not near ones.
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What does it mean to be short-sighted?
Short-sighted people can focus on near objects, but not distant ones.
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What are the causes of short-sightedness?
A person eyeball might be too long or the eye lenses are to powerful.
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What are the causes of long-sightedness?
A person eyball might be too short, or the eye lenses not powerful enough. This often happens as you get older.
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What are the three methods of treating sight problems?
Contacts, spectacles and laser eye surgery.
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What lens is used to treat long-sightedness, and what other lens is used to treat short-sightedness?
Short sightedness is treated by diverging lens, and long sightedness is treated by a converging lens.
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Where do long-sighted peoples light rays focus when focusing on near objects?
Behind the retina.
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Where do short-sighted peoples light rays focus when focusing on distant objects?
Infront of the retina.
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What are the advantages and dissadvantages of wearing contact lenses?
The advantages would be its less lightly to affect sport, and people preffer contact lenses over glasses. The dissadvantages would be that they have to be clean, otherwise they could cause infection and can be uncomftable.
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How does laser surgery work?
The patient is given a local anaesthetic, lasers are used to make a small, precise cuts int he cornea. These permanently change the shape of the cornea, and make it act like converging or diverging lenses.
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What happens to the focal length when a converging lens is thicker?
It shortens the focal length.
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What happens to the rays of light when the diverging lens is thicker?
It has a shorter focal lenght.
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What is power measured in?
Dioptres (D)
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What is focal length measured in?
Metres (m)
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Whats the difference in the focal length of a diverging lens?
It is negative.
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What lens produces real images?
A converging lens.
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What is refraction?
Refraction is the change in the speed of light rays, altering the direction.
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What happens to the rays of light as it enters a denser medium?
It slows down.
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What happens as you increase the refractive index?
The more the light slows down.
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What is total internal reflaction?
Any angle greater than the critical angle.
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What is the critical angle?
The angle at whitch the rays of light which entered a less dense medium are no longer refracted, as they are reflected.
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Explain TIR used in optical fibres?
Rays of light meetign the boundary between the cladding and core are totally internally reflected over and over till the end. The cladding must have a smaller refractive indes and the angle of refracting must be greater than the critical angle.
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What are the medical uses of ultrasound?
It is used to break down kidney stones, without the need of surgery.
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What are X-rays?
X-rays are electromagnetic waves with a short wavelength. They are albe to penetrate through soft tissue, and produce images of bones and organs.
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What happens to X-rays as their frequency is increased?
The higher the frequency, the more ionsising the x-ray is, because higher frequency waves transfer more energy.
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What is thermionic emmision?
When the negative electrode (cathode) which is a wire filament is heated and emits electrons.
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What is the lectron gun?
The wire filament.
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How do X-rays work?
In X-rays machine electrons are produced by the cathode, which is heated by a filament inside an efacuated tube (A vaccum tube), which accelerates electrons toward the anode, emeded in the anode is a tungsten target which converts some pe into x-rays
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Why do X-rays work in a vaccum?
This is because there are no molecules to scatter adn absorb the neerfy of electrons striking at a target.
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What does l stand for in the current calculation, and what is it measured in.
Current, and ampere, A.
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What does N stand for in the current calculation, and what is it measure in.
The number of particles per seconds 1/s.
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What does q stand for in the current calculation, and what is it measure in?
It is the charge carried by each electron, coulomb ,C.
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What is the relevance of kinetic energy in X-Rays?
In an X-ray electrons gain kinetic energy as they are accelerated throguh the vaccum by the pottenital difference.
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What is the unit for pottential difference?
Volts, V.
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What is kinetic energy measured in?
Joules, J.
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What is the mass of electrons measured in?
Kg.
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What is velocity measured in?
m/s
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At twice the distance fromt he source what is the intensity?
The intensity is one quarter as much because the area is four times great.
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Risks and benefits of X-rays.
X-rays can kill and damage living cells, especially to babies which exposure should be at minnimum. However, X-rays can provide a reliable diagnosis for quick treatment, and is non-invasive.
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What is action potential?
Action potentials is the electrical signals that control the heart muscles, these are generated by the hears natural peackmaker.
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What does the ECG show?
The ECG can show if a heartbeat is abnormal and can allow doctors to diagnose problems with patients heart.
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What is frequency measure in?
Hertz, Hz.
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What is the measurment for time in the pulse rate calculation?
Seconds, s.
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What is the purpose of a artificial pacemaker?
A pacemaker is used to monitor and detect irregular heartbeats. If an irregular heartbear is detected the pacemaker produces electrical signals to correct the heart rate.
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How does pulse oximetry work?
Two light sources, infared and visible red light, are used to test for the ammount of oxygen in blood. This is due to oxygenated blood absorbing more infared, this difference allow us to measure this.
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Properties of Alpha?
2 protons, 2 neturons - Relative mass of 4, heavily ionising, low penetration, and is affected by magnetic fields.
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Properties of Beta -?
Charge of -1, mas off 1/1840, weakly ionising, and has a low penetration.
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Properties of B+?
Charge of +1, mass of 1/1840, weakly ionising and has a low penetrating rate.
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Properties of Gemma (y)?
No mass, nor charge, not directly ionising, very hight penetration.
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Explain beta negative decay.
In beta negative decay, a neutron is transformed to a proton and a electron is released.
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Explain beta postive decay.
In beta positive decay, a proton is transformed to a netutron and a postiron is released.
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What side of the stability curve is B negative decay?
The left side.
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What side of the Stability curve is B positive decay?
Right side.
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Where does alpha decay happen?
This happens to isotopes with a greater than 82 atomic number.
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X and Y axis of the stability curve.
X axis = Proton Y axis = Neutron.
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Out of what quarks is a neturon built off?
1 up and 2 down quarks.
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Out of what quarks is a prorton built off?
2 up quarks an 1 down quark.
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What mass does a up, and down quark have?
+1/3
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What different charges do the up and down quark have?
The up quark has a charge of +2/3 and a down quark has the charge of -1/3.
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What happens in terms of quark in beta minus decay?
The down quark turns into a up quark.
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What happens in terms of quark in beta plus decay?
The up quark turns into a down quark.
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What are the danger of ionising radiation?
Low dosage of radiation allows your cells to recover, however, your body cant recover form high dosages of radiation. Ionising raditaion can also increase the changes of muations.
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What are the praucations whilst working with ionising radiation?
Wear protective clothins (e.g lead aprons), increase distance away from the radiation source, and reducting the lenght of type of exposure.
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What does a dosimeter do?
A dosimeter monitors the exposure to radiation the wearer has, so that it can be reduced.
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What do dentists do as a precaution whilst their taking X-rays?
Keep the X-ray pulse as short as posible, and go out of the room.
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What is palative care?
Some medical conditions are untreatable, and the doctors would reccomend palative care. Palative care involves minimising the tumour but not stopping it, but not curing it to improve quality of life.
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How do PET scanner work?
They trace for gemma rays produced by beta + decay emmiting positrons which annihilate with electrons producing gemma.
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External treatment of tumours:
This involves beaming gemma rays or x-rays into the patient by external machines, this can also destroy healthy tissues.
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Internal treatment of tumours:
If the patient takes in radioactive materials internally the radiation cab be targeted to reduce damage to healthy cells. An example of this is the radioactive isotope, iodine.
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What are particle accelertars, and what are their use?
Particle accelerators accelerate particles, and help scientist find out more about the subatomic particles that the world is made off.
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What force is used in cyclotrons?
Centripetal force is used in cyltorons which is caused by magnetic fields to keep the particle in circular motion.
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How do cyclotrons work?
Electrons are fired into the centre of the D-shaped enclosure, a strong magnetic field deflects the electrons so they follow a curved path, as they cross path between one D electrode to another a large voltage makes them accelerate.
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Why do particles in a cyltotron move in a circle?
Charged particles moving in a magnetic field experience a force at right angles to their direction of travels that make it move in a circular path.
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Making radioactive isotopes with particle accelerators?
Stable isotopes can be made radioactive by using cycltortrons to fire high energy particles into their nuclei. For example, xenenon gas changes into iodine 131, which is used in treatment of cancer.
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Why do scientist work collaboratively on internation research projects?
To share the cost of the project, and allows scientist to share their knowledge.
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What is an inelastic collision?
An inelastic collision is when mommentum is conserved, but kinetic energy is lost to heat.
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What is an elastic collision?
An elastic collision is when mommentum is conserved, and kinetic energy is conserved in a collision.
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What is annihilartion?
Annihilation is when a positron and electron colide and transform into energy.
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What is produced in the process of annihilation?
Two gemma waves.
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What do particles do in a solid?
Vibrate in a spot.
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What do particles do in a liquid?
Move past each over and move around randomly.
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What do particles do in a gas?
In gasses particles move around with high kinetic energy.
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What is the link between gas pressure and kinetic theory?
The particles in a gas are continuously movign in a ranom way and colliding with the containter wall. This force from these collisions producces pressure on the wall, this pressure is the same in all dirrection on the wall.
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What is abosolute zero?
Apsolute zero is -273 celsius, also, know as 0 kelvin.
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What is pressure measured in?
Kpa which is 1000 pascals.
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Other cards in this set

Card 2

Front

An ultrasound is pointed at the patient body, it will produce high-frequency sounds waves that are reflected by the features inside a human body.

Back

How does an ultrasound scanner work?

Card 3

Front

An endoscope allows keywhole surgery, it is build off optical fibres which provide live view of the internal structure in a patient.

Back

Preview of the back of card 3

Card 4

Front

A fluoroscope is used to study moving body structures, continous x-ray beams are passed through the body part which is being examined. The beam is transmited to a TV-like monitor so that the body part and its motion can be seen in detail.

Back

Preview of the back of card 4

Card 5

Front

A CAT scan is expensive, and the patient gets a relatively high dosage of radiation from it, which could result in mutations.

Back

Preview of the back of card 5
View more cards

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