0.10 Electric circuits

This simulation allows you to experiment with building circuits.

Circuits

1. Using physical components, set up the physical circuit which is described by the circuit diagram below and then draw the physical circuit:

   

2. Using physical components, set up a closed circuit which has one battery and a light bulb in series with a resistor.
   1. Draw the physical circuit.
   2. Draw the resulting circuit diagram.
   3. How do you know that you have built a closed circuit? (What happens to the light bulb?)
   4. If you add one more resistor to your circuit (also in series), what do you notice? (What happens to the light from the light bulb?)
   5. Draw the new circuit diagram which includes the second resistor.
3. Draw the circuit diagram for the following circuit: 2 batteries and a switch in series, and 1 lightbulb which is in parallel with two resistors.
   1. Now use physical components to set up the circuit.
   2. What happens when you close the switch? What does does this mean about the circuit?
   3. Draw the physical circuit.

Discussion : alternative energy

At the moment, most electric power is produced by burning fossil fuels such as coal and oil. In South Africa, our main source of electric power is coal-burning power stations. (We also have one nuclear power plant called Koeberg in the Western Cape). However, burning fossil fuels releases large amounts of pollution into the earth's atmosphere and contributesto global warming. Also, the earth's fossil fuel reserves (especially oil) are starting to run low. For these reasons, people all across the world are working to find alternative /other sources of energy and on ways to conserve /save energy. Other sources of energy include wind power, solar power (from the sun), and hydro-electric power (from water, e.g. dammed rivers) among others.

With a partner, take out the lists you made earlier of the item/appliances/machines which used electricity in the following environments. For each item, try to think of an alternative AND a way to conserve or save power.

For example, if you had a flourescent light as an item used in the home, then:

• Alternative: use candles at suppertime to reduce electricity consumption
• Conservation: turn off lights when not in a room, or during the day.

Topics:

• At home
• At school
• At the hospital
• In the city

Once you have finished making your lists, compare with the lists of other people in your class.

Potential difference

Potential difference

When a circuit is connected and complete, charge can move through the circuit. Charge will not move unless there is something to make it move. Think of it as though charge is at rest and something has to push it along. This means that work needs to be done to make charge move. A force acts on the charges, doing work, to make them move. The force is provided by the battery in the circuit.