an electrical property; it can either be positive or negative

the amount of electric charge flowing past a point in a circuit each second

the amount of energy transferred by each coulomb of charge, passing between two points in a circuit

the amount of energy transferred each second

Calculating with electric charge

Physics

Danger from electric shock

Short circuits and earth wires

Power of an appliance or electric circuit

The National Grid

Energy resources

In the Circuit components unit, pupils learnt how the resistance of filament lamps and diodes change with current and about the properties and applications of light dependent resistors and thermistors.

This unit covers UK domestic a.c. supply, mains wiring safety, energy changes in electrical systems, power ratings, and energy transfer. It explains the National Grid, transformers, energy sources, and calculations for energy changes and power transmission efficiency.

Mains electricity

An ammeter shows a steady reading of 1 A. Which of the following statements describes what this means?

Match these symbols for quantities to the symbols used for their units.

If 22 C of charge flows past a point in 5.0 s at a steady rate, the current is {{}} A.

66 J of energy is transferred to a lamp when 5.5 C of charge flows through it. The potential difference across the lamp is {{}} V.

The potential difference across a television is 230 V and a steady current of 0.39 A flows through it. How much energy does the television transfer every second?

An electric fan has resistance 5.2 Ω. When a current of 2.3 A flows through the fan, its power is …

charge flowing past a point in a circuit per second

a property that can either be positive or negative

energy transferred per unit charge passing between two points

Match each of the following quantities to the correct definitions.

Match each of the following quantities to the correct measurement units.

{{}} is the amount of energy transferred per second.

positive in some metals and negative in others

A metal is made of ions and free electrons. What is the charge on the ions?

The current in B is half the current in A.

The current in B is twice the current in A.

The resistance in B is twice the resistance in A.

The p.d. across the battery in B is twice the p.d. across the cell in A.

In circuits A and B, all of the cells are identical and all of the lamps are identical. Which of the following statements are correct?

A mains appliance has a current of 3.50 A through it. The power of the appliance is {{}} W (to 3 sf).

Calculating with electric charge

Lesson outcome