Electricity is essential to the modern world. Control of electricity allows us light on demand and allows us to make all of the electronic devices (including mobile phones) we use every day work.

In this topic you will learn what an electric current is and to define the quantities potential difference and electrical resistance. You will also cover the current and potential difference characteristics for several components, including resistors, filament lamps, diodes and LEDs. In addition you will learn the basic rules for current, potential difference and resistance in both series and parallel circuits.

Specification links

• Set 1 - Sections 4.2.1, 4.2.2 and 4.2.5

• Set 2&3 - Sections 6.2.1 and 6.2.2

Task 1b: Listen to the podcast to get an overview of the unit.

Task 2c: Make notes that:

• Explain how objects can become charged by friction.

• Explain how two rods of the same charge would interact with each other, and how two rods with opposite charge would affect each other.

• Draw the electric field lines around a positively and a negatively charged sphere.

• Describe how the strength of the force changes as the objects move apart.

• Explain how static shocks can occur - use this simulation to help.

• Explain why a person’s hair will stand on end when they hold a Van de Graaff generator.

Task 3c: Make notes that:

• Draw and label the circuit symbols and explain what each component does - this worksheet might help you.

• Define electrical charge and Define electric current.

• Explain how an ammeter should be connected in a circuit.

• Use this simulation to build the circuits on slide 11.

• Explain how the current changes as you add more components.

• Explain how the current changes as you add more cells.

• Give the word and symbol equation to calculate electric charge, and the units of each quantity.

• Calculate the answers to the practice questions on slide 15 and check your answers - worksheet here

Task 4c: Make notes that:

• Define potential difference and explain, in terms of energy, what a potential difference of 1 volt means.

• Write the equation to calculate potential difference and rearrange it to calculate energy transferred and charge.

• Calculate the answers to the questions on slide 12 and slide 14. Check your answers

• Define resistance and Give the unit.

• Write the equation to calculate resistance and rearrange it to give potential difference and current.

• Calculate the answers to the questions on slide 21. Check your answers

• Explain the factors which affect the resistance of a wire.

• Sketch a graph current / potential difference graph for a resistor at a constant temperature and Describe the relationship between them.

Task 5c: Make notes that:

• Write the independent, dependent and control variables and write a hypothesis for the investigation.

• Write a detailed method for carrying out this required practical.

• Calculate the resistance for each length of wire using the current and potential difference values given on slide 10.

• Write a conclusion explaining how the resistance of a wire varies with length.

Task 6c: Make notes:

• Write a detailed method for carrying out this required practical.

• Draw the circuit diagram for the experiment

• Sketch and label the current / potential difference graphs for the following components: filament lamp, diode, thermistor and light dependent resistor (LDR)

Task 7d:

• Give Ohms's law - include the symbols and units.

• Use the simulation on the right to explore how changing potential difference and resistance affect the current that will flow.

• Calculate the total resistance for the circuit you made for task 7c.

Task 7e:

• Explain the rules for:

  • Current in a series circuit

  • Potential difference in a series circuit

  • Calculating the total resistance of a series circuit.

Task 8d: Make notes that:

• Explain the rules for:

  • current in a series circuit.

  • potential difference in a series circuit.

• Explain why adding extra resistors in parallel DECREASES the total resistance of the circuit.

Complete the quiz to make sure you understand this unit.