ScienceOnline is an interactive resource for students and teachers of science.
The site provides access to a range of activities related to the New Zealand science curriculum for Years 9-11. Both Astronomy and Earth Science have been included as well as the core science areas of Physics, Chemistry and Biology. There are interactive notes and diagrams, self-marking tests, and useful links to other science websites. The site is completely up to date with NCEA requirements at Year 11 with details of achievement standards linked to topics in each of the five subject areas.
ScienceOnline has been developed by Peter Biggs, former science teacher and author of the Blue Science Book, and Sandy McGivern, science teacher, who manages the site.
In this document:
An electric circuit provides a complete path for the charges (the current) to move from one
terminal (called positive +) to the other
terminal (negative -).
The current must always pass through an electrical component. If this component is bypassed the circuit is said to be short-circuited and damage will occur to the wires or the
Every circuit you make must be checked to avoid such a short circuit. This
can be done by using your finger to trace the path of the current from
the positive terminal of the power supply back to the negative terminal.
A simple circuit
A simple circuit can be drawn incorporating two light bulbs and a switch.
Press the red button to complete the curcuit
Another simple circuit
In the following circuit, the three switches S1, S2 and S3
have an effect on the circuit in different ways.
Tracing the path of the current on the circuit diaram will show the following:
- Closing switch S1 only will leave both lamps unlit because the circuit is
- To complete the circuit, both switch S1 and either (or both) switches S2
and S3 need to be closed.
- Closing switches S1 and S2 will make only lamp A light up.
- Closing switches S1 and S3 will make only lamp B light up.
- Closing switches S1, S2 and S3 will make both lamps A
and B light up.
Test this out for yourself. Click on a switch to turn it on or off.
Tracing the current path in the lab
When you construct circuits in the lab it is not always obvious how the
current flows by looking at the mixture of wires and lamps. The only way to see
exactly what is happening is to trace (using your finger) the path of the
current from one terminal of the battery or power pack through the connections
to the other battery terminal.