physics

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how do smoke precipitators work?
metal grids are installed and are connected to a high voltage. the dust becomes positively charged as it passes through. the dust is attracted to negatively charged plates where they form large particles and fall back down
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what colour are the 3 pin plug wires?
live - brown, neutral, blue, earth - green/yellow
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what should the current rating be on the fuse in relation to the normal current that is in the appliance?
just above
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give the key features of waves and what they mean
rarefraction - low pressure, commpression - high pressure, wavelength - distance between 2 disturbances, frequency - no of waves produced in 1 sec, amplitude - max disturbance by a wave
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what can ultrasound be used for?
medecine, scanning, breaking kidney stones, speed of blood flow, detect tumors, prenatal scanning
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what is the frequency of ultrasound?
20000 Hz
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what is radiation measured in?
number of nuclear decays emitted per second
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what is an alpha particles?
a helium nucleas made up of 2 protons and two neutrons
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how does the nucleas of the new atom differ to the original?
different element, 2 fewer protons and neutrons, atomic no decreased by 2, mass number decreased by 4
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how does the atom decay in a beta emission?
changed a neutrons into a proton and an electron, the electron ejected is a beta particle
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what are tracers used for?
tracking the dispersial of waste, find leaks and blockages and routes of pipes
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how to smoke detectors work?
the contain an alpha emitter, emitted particles cause air to ionise, and the ions are attracted to electrodes. when smoke neters, the alpha particles are absorbed by the smoke particles, less ionisation take place so an alarm sounds
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what do nuclear pwoer stations use to create power?
uranium
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what do power stations use steam for?
to drive turbines which turn generators to produce electricity
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what are the uses of low orbit satellites?
imaging, weather, military
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what are the uses of high orbit satellites?
communications, weather
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if a projectile is launched horizontally, what will the projectile have?
a constant horizontal velocty and a steadily increasing vertical velocity
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how are frequences between 30MHz and 30GHz affected by the earths atmosphere?
they pass through
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frequencies about 30GHZ?
reduced in strengh or even stopped and are absorbed and scattered by rain and dust
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below 30MHz?
reflected by the ionosphere
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why are satellite dishes curved?
to focus all the microwaves onto the retriever in the middle
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what are the features of coherent waves sources?
have the same frequecny, are in phase and have the same amplitude
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what is constructive interference?
when identical waves arrive in phase at a point which produces a waves with a larger amplitude
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what is destructive interference?
occurs when identical waves arrive out of phase
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what is path difference?
an odd number of half wavelengths (destructive), an even number of half wavelengths (constructive)
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how do polarising lenses work?
by absorbing light that's reflected of shiney surfaces
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what is the refractive index?
a measure of how much the medium refracts light rays across a boundary
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what colour light refracts the most?
blue/violet
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what is the focal length?
the length between the centre of the lens and the focal point
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Other cards in this set

Card 2

Front

what colour are the 3 pin plug wires?

Back

live - brown, neutral, blue, earth - green/yellow

Card 3

Front

what should the current rating be on the fuse in relation to the normal current that is in the appliance?

Back

Preview of the front of card 3

Card 4

Front

give the key features of waves and what they mean

Back

Preview of the front of card 4

Card 5

Front

what can ultrasound be used for?

Back

Preview of the front of card 5
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