Flashcards
Sem título
Flashcards do conjunto (25)
- 1what charges repel and what charges attract ?like charges repel and unlike charges attract
- 2what is electrostatic phenomena caused bythe transfer of electrons
- 3static electricity is the movement of electrons ...- a positive charge due to lack of electrons
- a negative charge due to an excess of electrons - 4ionscharged atoms or molecules
- 5what can the chance of receiving an electric shock be reduced by ?-correct earthing
-use of insulating mats
-using shoes with insulating soles - 6what can reduce the build up of static charge electricity and howanti- static sprays, liquids and cloths by carrying the charge away through the conducting material
- 7what can static electricity be useful for ?restarting the heart when it has stopped ( defibrillator)
- 8what are steps of using a defibrillator1. paddles charged
2. good electrical contact with the patients chest
3. charge passed through patient to make heart contract
4. care taken not to shock operator - 9what can static electricity also be useful for ?electrostatic dust precipitators to remove smoke particles etc from chimneys
- 10how do electrostatic dust precipitators work?- metal plates/ grids put into chimneys with negative charge
- dust particles gain electrons as they move through the grid
- (negative) dust particles attracted to earthed plates
-dust falls back down the chimney/ removed at intervals - 11what is charge carried around a circuit by?negatively charged electrons
- 12what is current measured inAmperes(A)
- 13what does a resistor do?limits the amount of current flowing in a circuit
- 14what is resistance measured in ?ohms
- 15what do longer, thinner wires have?have more resistance so allow less current to flow
- 16what is voltage( potential difference) measured in ?volts
- 17what is the live wire in a plug?is brown and carries the current into the appliance
- 18what is the neutral wirecompletes the circuit and is blue
- 19what is the earth wireis green and yellow and carries away charge from the appliance if a fault causes the casing to become live
- 20what happens if a fault causes a surge in current?fuses break and prevent current from flowing. This stops overheating
- 21what are circuit breakers?fuses which can be reset so they do not need replacing like fuses do
- 22why do double insulated appliances not need an earth wire?they do not have any exposed metal parts so they cannot become live
- 23current flows in ... from a batteryone way( direct current)
- 24why does mains electricity alternate?so the electrons vibration both directions
- 25—
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- FlashCards sobre Sem título, criado por Emer Neave em 14-03-2016.
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- Emer Neave
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