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how can a material become elctrically charged?
an insulating material being rubbed against another insulating material
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do electrons have anegative or positive charge?
negative
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when two bits of insulating material becomes charged, electrons transfer from one material to another leaving ....
on material positivley charged and one material negatively charged.
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how do dusting brushed work?
they are charged so that they attract dust
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how can a charged object be discharged?
by being earthed, transferring electrons from the object to the earth
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how can static electricity become a nuisance?
dirt and dust can be attracted to television screens and computer monitors
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what happens when two insulating materials with the smae charge go near eachother?
they repel eachother
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what happens when two insualting materials with different charge go near eachother?
they attract eachother
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what are atoms and molecules that are charged up called?
ions
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if ions have an excess of electrons are they .... a)negatively ions b)positive ions
negativley charged
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how can the chance of recieving an electric shock be reduced?
making sure appliances are earthed, using insulation mats, wearing shoes with insulatng soles
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how can static electricity be used to spray paint?
the car is poisitvely charged and the paint is negatively charged meaning that the fine spray is attracted to the car.
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how does the paint become negatively charged?
the paint gains electrons as it passes through the nozzle which is negatively charged
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how do smoke precipitators work?
remove smoke from chimneys by attatching metal grid which is negatively charged attracting the positively charged dust.
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what is a circit?
a complete loop that allows electrical current to flow
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electrons flow in a circit from the ....
negative elctrode to the positive elctrode
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what is resistance?
how hard it si to get current to flow through a componment
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what is resistance measured in?
ohms
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what are the two types of resistors and that do they do?
a fixed resistor - has constant resistance. A variable resistor -has a changable resistor
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what is the formula to work out resistance?
resistance = currant / voltage
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what colour is the live wire?what is its job?
brown. carries the current to the appliance
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what colour is the neutral wire?what is its job?
blue. completes the circit and carries the voltage away from appliance.
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what colour is the earth wire?what is its job?
green and yellow. it stops the appliance becoming live, acts as a safety wire/
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appliances with outer cases made of insulators dont have an earth wire, why?
they are double insulated so they cant become live.
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what kind of appliances have an earth wire?
appliances with outer metal cases so they dont become live
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what are the stages to an appliance becoming live and the solution to this problem?
a fault causes the appliance to become live. The circuit becomes shorter as earth wire has less resistance. The fuse melts. The circuit is broken. The appliance and use is protected.
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what are fuses and circuit breakers also known as? Whta is their job?
safety devices. Designed to break a circuit if a fault occurs.
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what is a fuse?
a short thin wire, with a low melting point.
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what is the equation to work out power?
power = currant x voltage
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what is the power rating?
tells you how quickly electrical energy is being changed into another form within the device.
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what is ultrasound??
waves with frequencies above the upper limit of the human hearing range.
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what type of wave does ultrasound travel in?
longitudinal waves
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what are the key features of a wave?
rarefaction - are of low pressure. compression - area of high pressure. wavelength - distance between corresponding points. frequency - the number of waves made in one second.
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what are the uses of ultrasound?
ro measure speed of blood, to detect gallstones and tumours, for pre-natal scanning (for a baby)
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how does ultrasound break down kidney stones?
ultrasonic waves cause kidney stone to vibrate, the stone breaks up and can be then passed through urine.
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what are the two advantages over x-ray imaging?
able to produce images of soft tissue, it doesn't damage living cells.
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what do radioactive materials give out and from where?
nuclear radiation from the nucleus of each atom
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during the decay of an atom during radioactivity where is alpha particle found?
in a helium nucleus.
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during the decay of an atom during radioactivity where is beta particle found?
it is a fast moving electron
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what is radiation measured by?
the number of nulcear decays emitted per second
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what happens during alpha emission?
the atom decays by ejecting an alpha particle from the nucleus.
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what happens during beta emission??
the atom decays by by changing a neutron into a proton and an electron. the electron is ejected from the nucleus is a beta particle.
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what is half life?
it is the time it takes for the half un-decayed nuclei in a radioactive substance to decay.
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what does it men when a radioactive substance has a very long half life?
it means that the substance stays active for a very long time.
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what is background radiation?
it occurs naturally in our environment and radiation is released during this.
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what is the majority of the background radiation from?
radioactive substance in rocks and soil, cosmic rays from outer space.
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what are radioisotopes used for in terms of radiation ?
they are used as tracers to track dispersal of radioactive waste, find leaks and blockages in underground pipes
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how does a tracer work when looking for a leaks and blockages in an underground pipe?
gamma rays are put into the pipe and then traced from above ground to find leaks and blockages
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what do smoke detectors contain? what is it also know as?
Americium-241. an alpha emitter
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how does a smoke detector work?
the alpha particles that are emitted are absorbed by smoke particles. less ionisation takes place which means less current now flows, meaning the alarm will sound.
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why are x-rays and gamma rays similar??
because they are both electromagnetic waves and both have similar wavelengths.
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what can x-rays be used for ?
to build up a picture of the inside of a body
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what can gamma rays be used for?
to treat cancer and to steralise medical equiptment
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how are x-rays made?
by firing high speed electrons at metal targets.
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how do gamma rays work when treating cancer?
a wide beam of rays is focused on the tumour inside of the body from a source outside of the body, the beam is rotated around the tumour which minimises risk on the rest of the body
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what do conventional power stations use?
they use fossil fuel by burning it, this produces heat and steam
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what do nuclear power stations use?
they use uranium, a nuclear reaction takes place, this is called fission.
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what is the common ground between conventional and nuclear power stations?
they both use steam to turn generators and produce electricity
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what is nuclear fission?
the process in which heat energy is released when a radioactive nucleus splits.
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how does nuclear fission work?
it works by te uranium nucleus absorbing an extra neutron meaning it splits which releases energy and more neutrons
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what does nuclear fission produce which can be dangerous??
radioactive waste
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what is nuclear fusion
heat energy is released when two nuclei join together, it happens easily in stars.
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can nuclear fusion happen at high or low temperatures?
very high temperatures
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why isnt cold fusion a realistic method of energy production?
because it has only ever been proved once in 1989 an has yet to be done again.
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Card 2

Front

do electrons have anegative or positive charge?

Back

negative

Card 3

Front

when two bits of insulating material becomes charged, electrons transfer from one material to another leaving ....

Back

Preview of the front of card 3

Card 4

Front

how do dusting brushed work?

Back

Preview of the front of card 4

Card 5

Front

how can a charged object be discharged?

Back

Preview of the front of card 5
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