Modelling electricity – Main activity

1. Modelling electricity – Main activity By David Bailey Based on an idea by Bob Kibble - Moray House School of Education, Edinburgh Contents 1. Preparation 2. Setting up the model 3. How to use the model 4. Discussion 5. Other things to consider…

2. Before you begin… • Remember to remind students that this is a model for electricity, it isn’t what really happens. • This is a ‘scientist’s story’ that will help you to learn the rules for electricity.

3. 1. Preparation • Making the electricity hats and charges. You will need… • Sheets of thin card • Paper to make headbands • Scissors, glue and/or sticky tape • Print out the circuit symbols onto thin card. • Fold along the dotted lines so that the circuit symbol shows. • Glue or tape these in place. • Fasten a paper band around the base of the circuit symbol. Take care that this doesn’t have sharp edges as this will go around the head and rest on the ears. • Photocopy the electron sheet onto paper for as many students as you will have in your model. • Crumple up the paper so that the word electron is on the inside and is not visible from the outside.

4. 2. Setting up the model • Assemble your students in a circle or similar closed loop. • Nominate three students as components (cell, bulb, switch). • Give each of these the appropriate hat to wear. • Nominate two other students to operate the switch on the real circuit and the PowerPoint slide of the model. • Give each student a crumpled up piece of paper (charge) • Have a circuit set up using the same components you have in your model. • Also have the PowerPoint slide showing the model available.

5. 3. How to use the model All parts of the circuit prepare by holding their charges in one hand (the same hand for all charges) and holding out the other hand ready to receive a charge from a neighbour. The switch says “switch on” and allows charges to start moving. “switch on”

6. As you start off the model circuit ask the other students to close the switch in the real circuit and click the “click here to close the switch” button on the PowerPoint slide of the model.

7. “pass” The cell controls the rate at which the charges are passed around the circuit by providing the energy (or push) for the charges to move. They do this by saying “pass” (or “push” or “go”). They can speed the charges up by saying this more often or slow them down by saying this less often.

8. At the same time, model this on the PowerPoint slideshow by pressing the “click here to increase voltage” button. Also add a second cell in series to the real circuit.

9. The charges flow around the circuit through the wires and bulbs.

10. When the charges pass a bulb it transforms some of the electrical energy of the moving charge into thermal and light energy. This makes the bulbs glow. The ‘bulb’ should model this. The charges pass through the bulb without being used up.

11. 4. Discussion • Remember to “switch off” before discussing the model. • Once you have run the model a few times and the students are comfortable with how it works, use the model to consider the following questions… • What happens if you use a battery with a bigger voltage? • What happens if you add another bulb in series? • What happens if you add another bulb in parallel? • Where in the circuit do you have to place an ammeter which measures the flow of electricity? • Where in the circuit do you have to place a voltmeter which measures the difference in energy of each of the charges? • What exactly are the things moving around the circuit?

12. 5. Other things to consider… There are more questions in the things to think about section of the PowerPoint slideshow You may also wish to discuss limitations of this model with more able students. This can also be used with older pupils (e.g. GCSE or A-level) when revisiting electricity. A similar model could also be used to model capacitors. This model has also been used with younger pupils in KS2 and to train ITT students.