Electricity is a major part of our modern world and many people depend on it daily to work without fail (including us right now reading this!). We do this all the time without ever really having to stop and think how electricity gets to us from where it is made.
This shows Nikola Tesla (inventor of most of the modern electronic world) sitting next to one of his Tesla Coils knowing that he would not get electrocuted from the +100,000 volts.
Although it would be cool to see electricity flying around the room from one place to another, it’s not safe for the general population and also EXTREMELY inefficient. So instead we use “Conductors” and “Insulators” to make sure that energy is transferred safely from one place to another.
You would’ve / should’ve learnt about conductors and insulators in Year 7, but as a reminder there are 2 types, Thermal and Electrical. These mostly overlap and have similar properties.
This graphic explains “Thermal” Conductors and Insulators
This graphic shows some “Electrical” Conductors and Insulators
An electrical conductor is a substance in which electrical charge carriers, usually electrons, move easily from atom to atom with the application of voltage. Conductivity, in general, is the capacity to transmit something, such as electricity or heat.
An electrical insulator is a material whose internal electric charges do not flow freely; very little electric current will flow through it under the influence of an electric field. This contrasts with other materials, semiconductors and conductors, which conduct electric current more easily.
What makes a good Conductor? Practical
Aim: To test different materials to see their conductive properties
Hypothesis: Not all materials will pass electricity
Method: Build a simple circuit of battery and light bulb, complete circuit using a variety of different metals, paper, plastic, wood, graphite (or lead from a pencil).
Keep the voltage constant
Observe and record the brightness of the light bulb.
Extra: Try adding more lights to the circuit, does it change the brightness?
Discussion
Spend some time looking at your results and try to write down 2-3 sentences of how you might explain what you observed. What happened:
- to the brightness of the light?
- when you changed the metals?
- if you changed the voltage?
Simple Circuits
For the remainder of the lesson we are going to be refreshing our knowledge on Series and Parallel Circuits. How to draw them and how they work. Some of this content is also covered in Year 7 Circuits.
Using the following link, make the sample circuits below. Record your results in the table
https://phet.colorado.edu/en/simulation/circuit-construction-kit-dc
| Single globe | Globe in Series | Globes in Parallel | |
| Brightness | |||
| Current (A) | |||
| Voltage (V) |
Questions
1. Describe what happened to the current when another globe is added in series.
2. Use your knowledge of resistance to explain why this happened.
3. Adding another globe in series makes all the globes duller. Explain why.
4. Explain why adding globes in parallel makes no difference to their brightness.
Quiz
If you want to challenge yourself and review what you have learnt try this Quiz for homework.
Mr Danic 
