CHAPTER 5 Flashcards
(47 cards)
What is the equation for energy transferred from the mains
Energy = power x time
What is the equation for power supplied
Power = current x potential difference
How do electrical appliances waste energy
Heating the surroundings
Friction in moving parts
Equation for efficiency
Efficiency = output/input x100
What is charge flow?
The electrons being forced round a circuit
Equation for charge flow
Charge flow = current x time
When the charge flows around a circuit for a given time, the energy supplied by the battery is equal to what?
The energy transferred to all the components in a circuit
Why does a resistor get hot when charge flows through it?
Energy is transferred to the resistor because electrons collide with the resistor ions, heating it up
What is the equation for power?
Power = energy/time
What is the current in an electrical appliance?
The current is the charge that flows through it each second
What is the potential difference of an electrical appliance?
The energy that is transferred to the appliance by the charge passing through it
Equation for power supplied?
Power = current^2 x resistance
What does the earth wire do?
It carried the current into the earth if something goes wrong
Why are plugs, sockets and cables made of insulators?
To stop them carrying a current
What is the potential difference of the earth wire?
0V
Why are the pins made of brass?
Brass is a good conductor and doesn’t rust
What does the fuse do?
If the current gets too high, it melts and cuts the live wire off
Which is the brown wire?
The live wire
Which is the blue wire?
The neutral wire
Which is the yellow and green wire?
The earth wire
Why is plastic used?
It is a good insulator so you don’t get an electric shock
What are two core cables used for?
Appliances with plastic cases
Why must some wires be thicker than others?
Carry different currents
What happens when a plug short circuits?
The live wire touches the neutral wire
