P5 Flashcards
What are battery devices?
Battery devices can be used anywhere but plugged devices must be used near a plug.
What do batteries do?
Batteries transfer energy from chemical potential by electric current whearas plugs directly supply electrical energy.
How are devices that use plugs and devices that use batteries the same?
Both transfer energy to electrical devices.
Both must be connected to the device.
What is electrical current?
flow of charge around a circuit (through a conductor).
What is AC?
AC means alternating current and the current constantly changes direction
What is DC?
DC is direct current and it means that the current flows in one direction only ( examples cells and batteries )
What is mains electricity?
It is the electricity you get from power sockets. It is also a alternating current.
How much volts and hz does the mains electricity have?
About 230V and has a frequency of 50Hz
What are the advantages and disadvantages of overhead cable?
Advantages:
• Relatively cheap to link between tall towers.
• Easy access to maintain cables.
• Open to air cooling of cables.
Disadvantages:
• Ugly, ruin landscapes.
• Vulnerable to the weather.
• Must cut across large amount of land.
What are the advantages and disadvantages of underground power cable?
Advantages:
- They take up less space
- It doesn’t look ugly ( because it’s underground )
- weather can’t stop it
Disadvantages:
• Very expensive to put miles and miles of cable underground. Lots of digging.
• Maintenance would be harder, would have to dig them up.
• The cables can get hot, hard to cool underground. Must therefore be thicker.
• Would need to clearly mark everywhere they are, wouldn’t want someone digging where they shouldn’t
Which of the following two actions are performed by a step-up transformer?
Increase the voltage and decrease the current
Which of the following two actions are performed by a step-down transformer?
Decrease the voltage and increase the current
Why is it beneficial to transmit electricity through cables to our homes at a high potential difference?
Transmitting the electricity at a high potential difference results in a lower current being used so less energy is transferred to the surroundings due to heating of the cables.
Why is the potential difference of electricity reduced before it is supplied into our homes?
Decreasing the potential difference makes the mains electricity safe to use at home.
How do fuses work?
The fuse breaks the circuit if a fault in an appliance causes too much current flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire which melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit.
