Domestic Electricity Flashcards
What is the equation for current?
Q=IxT
What is the equation for electrical power?
P=IV
or
P=E/T
How does a LDR (Light dependent resistor) work? (Resistance)
High resistance in the dark but a low resistance in the light
What is a thermistor?
A thermistor is a component that has a high resistance when cold but a low resistance when hot.
What is the acronym for LDRs?
L ight
U p
R esistance
D own
What is the acronym for thermistors?
T emperature
U p
R esistance
D own
When it is dark, the resistance of the LDR is high, meaning that its share of potential difference is…
High (light will turn on because it has a high enough potential difference to work)
When it gets light, the resistance of the LDR is low, so the share of the potential difference is…
Low (light won’t turn on because it doesn’t have a high enough potential difference to work)
When the thermistor is cold, the resistance is high, so the share of the p.d. across the thermistor is high. This means the share of the p.d. across the fixed resistor is …
Low (the fan is off as it doesn’t have a high enough p.d. to work)
When the thermistor increases in temperature its resistance decreases, this means that its share of p.d. decreases which means that the fixed resistor gets a … share of p.d.
Larger (the fan will turn on because the p.d. across the fan is high enough to make it work)
What is Alternating Current?
- current constantly changes direction in the circuit
- mains supply (230V)
What is Direct Current?
- Current travels one way around the circuit
- supplied by cells and batteries (1.5+V
What colour is the live wire?
Brown
What colour is the neutral wire?
Blue
What colour is the earth wire?
Green and yellow
How many volts do each of the different wires in a plug carry?
- Neutral 0V
- Earth 0V
- Live 230V
What is the function of the live wire?
Provides the current
What is the function of the neutral wire?
Completes the circuit
What is the function of the earth wire?
A safety wire to stop the appliance becoming live
Electrocute means…
Cause injury or death by an electric shock
What is the function of a fuse?
The fuse breaks/blows the circuit if a fault in an appliance causes too much current to flow
What do circuit breakers act as?
Resettable fuses
What is the equation for paying electricity?
Cost = Number of Units x Price per unit
