Describing the components in a circuit
Bulb - converts electric energy into light energy
Voltmeter - It measures the potential difference across a component.
Ammeter-Measures the current (number of electrons that pass every second).
Cell/battery-'pushes' electrons round the circuit
Switch-completes/breaks the circuit.
Diode-allows the current to go in one direction
Resistor-limits the current in a circuit
Variable resistor-Varies the current in a circuit.
Fuse-designed to melt/break the circuit when too much current goes through it.
Describing the components in a circuit CONTINUED
Heater-Converts the electric energy to thermal energy.
Thermistor-lowers its resistance as the temperature increases. E.g. kettle
LDR [light dependant resistor] - as the light intesity increases, the resistance of the circuit decreases.
Add the resistance in a series circuit.
Current is the same all the way round in a series circuit.
Voltage is shared between the components in a series circuit.
Current is different in a parallel circuit because it may split up at a junction.
The voltage is the same across each component.
How is resistance calculated?
Resistance (ohms) = voltage (V) / current (A)
1. Type -poor conductors, high resistance which means no current.
2.Length -lectrons collide more often in a long wire as atoms collide more often in a long wire than shorter.
3.Thickness -thin wire has more resistance as electrons more likely to collide with (metal) ions. Thick wire has less resistance and a thin wire has more resistance.
4. Temperature- the hotter the wire, the greater the resistance as the increased vibrations of electrons cause them to have a larger chance of ions capturing electrons.