Section 5 - Electricity Flashcards
What is a diode?
An electrical component where current can only flow in one direction.
What is a LDR?
Light dependent resistor. The resistance increases as light increases.
What is a thermistor?
A resistor where its resistance decreases the hotter it gets.
In a series circuit, is the current the same or different everywhere?
Same
In a parallel circuit, is the current the sane or different everywhere?
Different
How does adding a resistor in parallel reduce the total resistance of a circuit?
By adding another loop to the circuit, the current has more than one direction to go. This increases the total current that can flow around the circuit, An increase in current means a decrease in total resistance.
What does a.c mean?
The direction of the current in constantly changing direction
What does d.c mean?
The direction of the current will always stay the same.
What is the voltage of the UK mains supply?
230V
What is the brown wire called in a cable and what does it do?
It is the live wire and it carries the voltage
What is the blue wire called in a cable and what does it do?
It is the neutral wire and it completes the circuit so the electricity can flow
What is the green and yellow wire called in a cable and what does it do?
It is the earth wire and it is for safety. It carries the current away if something goes wrong.
How does a fuse work?
When the current passing through a fuse goes above its rating, it causes the wires in the fuse to melt, breaking the circuit.
In what ways are circuit breakers better than fuses?
Circuit breakers turn off much faster than fuses. They can also be reset, while fuses have to be replaced.
Note: you need to know circuit symbols
They are found on page 71 on the CGP guide
What is Current?
The flow of an electric charge around a circuit
What is needed for a current to flow?
A complete circuit and a potential difference
Why does the resistance of a component usually increase with temperature?
The ions have more energy, and so move around more. This makes it harder for the electrons to get through as they collide with the ions more.
Is an ammeter put in series or parallel to a circuit?
Series
Is an voltmeter put in series or parallel to a circuit?
Parallel
How does a fuse work?
A surge in current causes the wire in the fuse to heat up and melt. This breaks the circuit and stopping the electricity from flowing.
At what current should fuses/circuit breakers be rated at?
Just higher than the normal operating current
Why are circuit breakers better than fuses?
A circuit breaker can be turned back on, a fuse you have to replace
Circuit breakers turn off faster
