3 pieces of single-core insulating wire (bell-wire), each about 25 cm. long, bared at the ends; 11.5v or 2.5v light bulb; 11.5v battery (not rechargeable); 1 bulb holder; 1 screwdriver; 1 collection of everyday objects, eg. coins, rubber, wood, plastic, paper graphite (pencil lead), glass, string, chalk, cloth.
Pupils should work in groups of 3
you have already done the 'making a switch' activity from this site, you
could remind pupils that a paper clip was used to bridge the gap in the
Each group could be asked to list other materials/objects which they think would have served equally well
They might also be asked to compile a second list, of materials/objects which they think would not have been of use in bridging the gap. Each group should discuss each suggestion before agreeing on lists
Explain that some materials allow electric current to flow along them very smoothly. These are called conductors. There are certain materials through which, electric current can pass, but only with extreme difficulty. These are resistors. Finally, there are some materials, called insulators, which d'ont conduct electricity at all.
Show one of the collections of objects to the class. How might we test whether each is a conductor, a resistor or an insulator.
the pupils have come up with the idea of using the material to bridge a
gap in their circuit, each group should proceed to test a collection of
objects. The attached worksheet could be issued, requiring the group to
include each object in one of 3 columns (Conductors/Resistors/Insulators).
As they finish, ask each group to compare their results with the lists which they completed at the beginning of the lesson..