Year 9 Summer 1 - Electricity Part 2 Flashcards
Alternating Current (AC)
Current that constantly changes direction.
Direct Current (DC)
Current that flows in one direction.
Electric field
The area around a charged object where its force can be felt. The field is strongest when close to the charged object.
Mains electricity
UK mains electricity is an AC supply (used when plugging appliances in). It is 230V and has a frequency of 50Hz.
Static electricity
When two insulating materials are rubbed together, the friction causes electrons to move from one object to the other. The object that loses electrons becomes positively charged. The object that gains electrons becomes negatively charged.
Step-down transformer
Used to decrease the potential difference.
Step-up transformer
Used to increase the potential difference.
What colour is the live wire?
Brown
What does the live wire do?
Carries the current from the supply to the appliance.
What is the potential difference between the live wire and the earth wire?
230V
What colour is the neutral wire?
Blue
What does the neutral wire do?
Completes the circuit by carrying the current from the appliance back to the supply.
What is the potential difference of the neutral wire?
At or close to 0V.
What colour is the earth wire
Green and yellow
What is the earth wire?
The safety wire which stops the appliance from going live.
What is the potential difference of the earth wire?
0V
Does the earth wire carry current?
Only if there is a fault.
….. = Potential Difference * Current
Power = Potential difference * Current
Power = ….. * Current
Power = Potential Difference * Current
Power = Potential Difference * …..
Power = Potential Difference * Current
…… = VI
P = VI
P = …..
VI
What does P stand for?
Power
What does V stand for?
Potential Difference
What does I stand for?
Current
….. = (Current x Current) x Resistance
Power
Power = (….. x Current) x Resistance
Current
Power = (Current x …..) x Resistance
Current
Power = (Current x Current) x …..
Resistance
What does R stand for?
Resistance
….. = Power x Time
Energy
Energy = ….. x Time
Power
….. = (I x I)R
P
P = (….. x I)R
I
P = (I x …..)R
I
P = (I x I)…..
R
Energy = Power x …..
Time
….. = Pt
E
E = …..
Pt
What does E stand for?
Energy
What is the unit for power?
Watts(W)
What is the unit for Potential Difference?
Volts(V)
What is the unit for current?
Amperes/Amps(A)
What is the unit for resistance?
Ohms(Omega)
What is the unit for energy?
Joules(J)
What is the unit for time?
Seconds(s)
The National Grid
A system of cables and transformers linking power stations to consumers.
What is electrical power transferred through to get from power stations to consumers?
The National Grid
Why is The National Grid an efficient way to transfer energy?
It reduces heating losses.
What happens when two electrically charged objects are brought close together?
They exert a force on each other.
What do two objects that carry the same amount of charge do?
Repel
What do two objects that carry different types of charge do?
Attract
Is attraction and repulsion between two charged objects a contact or non-contact force?
Non-contact
