Resources: Materials for the Mission Assignment, such as cells x2, bulb, wires x x4 and a selection of bulbs and batteries (optional).
Handout: Space to record the results of the Mission Assignment. A table for the students to fill in and analyse different bulbs and batteries. Information sheets about various bulbs and batteries are included on the third page.
Revise learning of batteries and voltage from KS2. The students should recall that the strength of electricity is measured in volts and that batteries provide a source of electrical energy. They should also recall the purpose of switches and buzzers in electrical circuits.
Ask the students which of the batteries on the slide contains the most energy.
Complete the first part of the presentation, introducing voltage, and then recap drawing a circuit. Once complete, the students can explore any batteries, looking at the size, share and voltage, and then discuss any differences as a class. Then, they can complete the data mining task on the worksheet. Continue with the slides and then introduce the Mission Assignment on how bulb brightness changes in series and parallel circuits.
Optional demo: Have a collection of old batteries in different shapes and sizes to compare and discuss.
Career Film: Take a tour around Rolls Royce SMR's Heritage Museum in Derby to find out about Elliott Wyart's job. Elliott works as the Reactor Island Installation Assembly Manager for Rolls Royce SMR.
Expert Film: This is Elliott Wyart. Elliott works as the Reactor Island Installation Assembly Manager for Rolls Royce SMR. Listen to Elliott as he describes the role of voltage.
Voltage in Series and Parallel
The students will investigate the effect of cells arranged in series and parallel.
Build a circuit with two cells connected in parallel to a single bulb. Describe the brightness of the bulb. Then, build a circuit with the two cells connected in series to a single bulb. Describe the brightness of the bulb. Compare the brightness of the two bulbs. If you have a voltmeter, measure the voltage across the bulbs.
Support: Analysing bulb batteries. Ask the students to read through the information about different batteries and bulbs. Then, complete the table and record the information in the correct place.
Challenge: This activity could be extended by looking at your selection of bulbs and/or batteries. Ask the students to record their power rating and voltage rating. Then, describe the brightness of the bulb qualitatively. They could also describe their designs and uses.
Discuss as a class why lighting in the home is on parallel circuits and not series circuits. Ask the students to decide if traffic lights are series or parallel and ask them to justify their answers.
An electrical cell is a 1.5V chemical power source e.g. AA/AAA battery (the name battery in this context is a misnomer).
The term battery in a physics context is a group of two or more cells connected in series.
Voltage is an overarching term to describe the amount of energy per unit of charge. In other words, how much energy is stored in the electrons that flow around the circuit? It is measured in volts (V).
There are two types of voltage:
Potential difference – the difference in the amount of energy entering and the amount of energy leaving a component per unit charge.
EMF (electromotive force) – the amount of energy converted from chemical potential energy to electrical energy per unit of charge.
Typically, a component is described with the term potential difference and a cell or battery is described as having an EMF.
Cells in series add together their EMFs and create a larger EMF. This means energy is supplied to the circuit at a higher rate compared to just one cell.
Cells in parallel do not add together and effectively act as one cell. Although this does not mean a higher overall EMF, it does mean the cells will last longer.
Components in series share the total potential difference. For example, two identical bulbs connected to a 1.5V cell in one series loop receive 0.75V each.
Components in parallel do not share the total potential difference as they are on independent loops. For example, two identical bulbs connected to a 1.5V cell in parallel receive 1.5V each.