Current, potential difference and resistance

What is needed for electrical charge to flow through a closed circuit?

Potential difference

What is electrical current?

A flow of electrical charge

What do switches do?

Control the flow of electricity.

What does a diode do?

Allow currents to flow in only one direction.

What does a fuse do?

Breaks if there is too much current.

What does a fixed resistor do?

Has a provided amount of resistance that cannot be varied.

What does a variable resistor do?

Its amount of resistance provided can be modified.

What does a voltmeter do?

Measure potential difference - added in parallel.

What does an ammeter do?

Measure current - added in series.

What happens to a thermistor when temperature increases?

The resistance of a thermistor decreases.

What happens to a LDR when light intensity increases?

The resistance of an LDR decreases.

When is the the application of thermistors required?

In circuits eg a thermostat.

What is potential difference?

The driving force that pushes the charge round.

What is resistance?

Anything that slows the charge down.

What does the current flowing through a component depend on?

The potential difference and resistance of the component; the greater the resistance of the component the smaller the current for a given potential difference (pd) across the component.

What is the equation for potential difference?

Potential Difference (V) = Current (A) x Resistance (Ω)

What is another word for potential difference?

Voltage.

What should happen if the resistance remains constant in a component?

The potential difference and current should increase proportionally.

What is charge?

A measure of the total current that flowed within a certain period of time.

What does the total charge through a circuit depend on?

Current and time.