electricity-p5 Flashcards by abena bracewell

Q

what is current measured in

A

amperes

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Q

what is potential difference measured in

A

voltage

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Q

what is resistance measured in

A

ohms

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Q

what the equation for volt, amps and resistance

A

p.d = current x resistance
V=IR

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Q

what’s the equation of charge

A

charge= current x time

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Q

what’s the unit of charge

A

coloumbs, c

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Q

what’s the equation for power

A

power= current x potential difference

or

power = energy/time

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Q

what are step up transformers used for

A

to increase the p.d and decrease current

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Q

what’s the step down transformer used for

A

to decrease the potential difference and increase the current

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Q

what current reverses in direction

A

alternating current

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Q

what current moves in one direction

A

direct current

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Q

what is the direct current supplied by

A

the cells and batteries

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Q

what’s the alternating current supplied by

A

the mains supply

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Q

what voltage and hertz is the mains supply

A

230v and 50hz

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Q

what three wires are present in uk plugs

A

live wire, earth wire and neutral wire

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Q

what are the wires coated in

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A

plastic

Q

what colour is the earth wire

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A

yellow and green

Q

what colour is the live wire

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A

brown

Q

what colour is the neutral wire

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A

blue

Q

what the voltage of neutral wire

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A

0v

Q

what the voltage of live wire

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A

230v

Q

what the voltage of earth wire

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A

0v

Q

what is power measured in

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A

watts, w

Q

what’s energy measured in

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A

joules,j

what’s time measure in

seconds,s

what’s the fuse connected to

the live wire

what happens if the current gets too hot

fuse wire heats up, melts and breaks

what the national grid

a network of cables and transformers

what are the pins in a plug made out of and why

brass so it doesn’t rust

what’s are the plugs made out of and why

stiff plastic because their good insulators

how do u get 1000 miliamps into 1 amp

divide by 1000

how do u get 1amp into 1000miliamps

times by 1000

what the equation for energy

energy = power x time or energy = current x time x p.d

what’s the equation for energy in kilowatt hours

energy(kwh) = power(kw) x time(h)

what’s efficiency’s equation

efficiency = useful output/ total input x 100

how do you get from 1000watt to 1kilowatt

divide by 1000

how do u get from 1 kilowatt to 1000 watt

times by 1000

what the equation for potential difference

p.d = energy/charge or p.d = current x resistance