Safe Electricals Flashcards
What does a variable resistor (rheostat) do?
Changes the resistance.
What kind of wires have more resistance?
- Longer
- Thinner
How do we measure voltage (potential difference)?
Voltmeter in parallel.
What happens to the current as the voltage increases across a fixed resistor?
It increases
What happens to the current as the resistance increases for a fixed power supply?
It decreases
What is resistance measured in?
Ohms
What is the formula for resistance?
R = V/I
What colour is the live wire and what does it do?
Red, carries current to the appliance.
What colour is the neutral wire and what does it do?
Blue, carries current back to the supply from the appliance and completes the circuit.
What colour is the earth wire and what does it do?
Yellow and green, connects to the metal casing of the appliance so if the appliance becomes live the current will flow through the earth wire to the ground rather than through a person because it has less resistance.
What does a fuse do?
A fuse will melt if too much current flows through it, breaking the circuit before the current can flow to the appliance so that it can’t be damaged. It is connected to the live wire.
