P5 ELECTRICITY IN THE HOME Flashcards
what are the names of the 3 wires contained in an electrical cable?
Live wire, Earth wire and neutral wire.
what is each wire encased of and why?
Plastic, to stop the wires from touching and to prevent a short circuit. Also a good insulator.
What are the wires made of and why is it important?
Copper as its a good conductor of electricity.
What does a live wire do?
Carries live current.
What does an Earth wire do?
A safety that is needed to earth appliances with a metal case.
What does a neutral wire do?
Completes the circuit.
Whats the frequency of A.C?
1/time taken for 1 cycle
What is an oscilloscope?
An oscilloscope is used to show how an alternating potential difference changes with time.
Direct current flows…
In one direction only/
Alternating current repeatedly…
reverses its direction of flow.
Why does direct current flow only in one direction?
Because it has the electrons flowing steadily along the conductor from high to lower potential points.
Why does alternating current change direction?
As the wire spins and periodically enters a different magnetic polarity, the voltage and current alternate on the wire.
What is correct rating (a) for a fuse formula?
electrical power(watts)/potential difference(volts)
The energy transferred to a device is?
E=PT
The electrical power supplied to an appliance is?
P=IV (power = current(a) x Resistence(ohm)
How to calculate charge?
Charge flow,Q(Coulombs) = Current, I(amps,a) x time,t(seconnds,s)
When charge flows through a resistor, energy is transferred to the resistor which…
Makes the resistor hotter.
Energy transferred to a resistor equation?
Energy,E = Charge flow, Q x Potential difference, V
Formula for efficiency?
Output power/input power (x100)
Formula for output power?
Efficiency x Input power
What does a domestic electricity meter do?
Measures how much energy is supplied.
Formula for useful energy used?
Efficiency x Energy supplied
