- Electrons always move in the same direction
- Potential difference is always the same
Example- Batteries
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What is alternating current?
- Electrons keep reversing direction because potential difference is constantly reversing
- Sometimes positive, sometimes negative
Example- Mains electricity
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How many cycles does mains electricity go through?
50 cycles every second, meaning it has a frequency of 50Hz
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What is the equation for frequency?
1/the time for one cycle
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What is the National Grid?
A series of transformers that change the potential difference of the electricity and wires that send electricity around the country
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What is the disadvantage of sending electricity at a high voltage?
High voltage electricity is dangerous
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What is the equation for electrical power?
Electrical Power(W)= Current(A) x Potential Difference(V)
P=IxV
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Earth Wire
- Prevents electrocution
- Yellow and green
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Neutral Wire
- Returns the current to the main circuit
- Voltage should remain 0V
- Blue
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Live Wire
- Carries an alternating current with a voltage which alternates between 325V and -325V
- Red
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What is the plug fuse?
A thin piece of wire which melts if the current through it get's too large. It's a safety feature because it prevents the appliance cable from melting and causing a fire
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Cable Grip
A safety feature which ensure the wires don't come lose
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Live, Neutral and Earth Pins
Made of: brass
Reason: good conductor, hard so holds shape, doesn't corrode
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Inside of Live, Neutral and Earth wires
Made of: copper
Reason: good conductor, flexible, doesn't corrode
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Outside of the cable
Made of: rubber
Reason: doesn't conduct, flexible
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Outside of the plug
Made of: plastic
Reason: doesn't conduct, hard
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Why are some plugs double insulated?
If the outside of an appliance is entirely plastic you can't electrocute yourself, so you don't need an earth wire
Current(A)= Power(W)/Voltage(V)
Current= Charge flowing/ Time
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How do you chose a fuse for appliances?
An appliance needs a fuse which will allow a slightly higher current to flow through it then it would normally use
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Fuses are usually...
1A, 3A, 5A, or 13A
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What is the voltage of mains electricity?
230V
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What are the two Efficiency equations?
Efficiency= Useful energy/ Total energy (x100)
Efficiency= Useful power/ Total power (x100)
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Total energy is...
Useful energy + Wasted energy
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Other cards in this set
Card 2
Front
What is alternating current?
Back
- Electrons keep reversing direction because potential difference is constantly reversing
- Sometimes positive, sometimes negative
Example- Mains electricity
Card 3
Front
How many cycles does mains electricity go through?
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