Scientific Method: Electricity – The Light Bulb

Task 1: Create your own light bulb

Equipment: 2 x 50cm of copper wire; thin iron wire; glass jar with lid (punched with 2 holes); a battery; connecting wires with crocodile clips.

Run each of the copper wires through the two holes in the jar lid. Make small hooks shapes and run the thin iron wire between the two hooks, looping 2-3 times. Place the lid on the jar and connect to the battery.

Task 2: Find out about these:

You can use the two ISLE links as well as other resources that you can find on the internet.

1. How does a fluorescent light bulb work? Current flows through circuit to electrodes, Gas in the tube is argon to provide an inert atmosphere it is low pressure inside the tube. The electron emit photons at a UV frequency. Tube coated with phosphor, converts UV frequencies into visible light.

2. Why is Thomas Edison credited for inventing the light bulb? Who actually invented it first and when? Sir Humphrey Davey 1801, naked flames with a gauze around it. Joseph Swan credited with discovery 1860 but Eddison discovered it in 1879.

3. How was the scientific method used to develop the light bulb? Trial and error approach, tried different materials for the filament until he found one that worked. In efficient but necessary.

4. Who first generated electricity and how did this contribute to the invention of the light bulb? Allessandro Volta generated electricity. Allowed free use of electricity ashes discovered the battery. Michael Faraday invented power generator to produced sustained power which is required for lighting a bulb.

5. How did the invention of the light bulb change people’s lives? People could work at night.

6. Describe the ways that a fluorescent light bulb is inefficient. Mercury gas is poisonous, might leak out and poison people.

7. What is the future for artificial lighting? What improvements have there been since the invention of the light bulb?

The Light Bulb – Electrical theory

1) Lighting up a bulb using citrus fruits

Equipment: 2 oranges or lemons, 2 galvanised zinc nails or zinc strips, 2 copper nails or copper strips, copper wire, 2 connecting wires, crocodile clips, light bulb or LED light, voltmeter

Roll the citrus fruit with the palm of your hand to release the juices (but not too hard so that the skin splits!). Insert one zinc and one copper nail/strip into each fruit without actually touching one another. Attach copper wire to the copper nail/strip on one fruit to the zinc nail/strip on the other fruit. Complete the circuit with the connecting wires and the bulb as shown in the diagram below. If the bulb does not light up, replace it with the voltmeter to test whether an electrical current is generated.

Why do you think 2 fruits were used instead of one? (Try it out!)

How do citrus fruits generate an electrical current to light up the bulb?

Why do you think the fruit needed to be rolled first?

What similarities are there between the fruit in this experiment and a battery?

What can be used instead of lemons to power a light bulb?

Extension:

Design an investigation to find out which fruits or vegetables make the best batteries.