"How do globes operate?" Return to list of pracs

Aim: This activity is used to identify how to use small electric light globes.

Equipment: The equipment includes...  

• two wires;
• One 9V, C or D size battery;
• globe;
• masking tape.

Worksheet: "Electrical current pg 10-11"

Method: Tape with masking tape one end of one wire to the base of the battery. Tape one end of the another piece of wire to the top of the battery. Attach the other end of top wire to the metal casing of the globe. Tape one end of the bottom wire to the very base of the globe. They will conduct electricity and the globe will therefore glow!

Background knowledge: Good conductors of electricity require the material to allow charged particles to move freely through its structure. If charged particles (negatively charged electrons) cannot move easily through the material, then it is called an insulator. This is why wires are made of metal which as you have discovered are generally very good conductors. It is in the nature of metals to allow free moving electrons to move throughout its structure very easily. The electricity passes out of the base of the battery through the wire to the base of the globe, through the filament in the globe. This special type cof metal heats up when current is passed through it and as a result the gas within the globe also glows under heat. The electricity then collects on the casings of the globe and returns to the top of the battery.

Get students to connect according to the worksheet and test various hypotheses until they get the right combination.

For the globe to work:

• The circuit requires a full path for electricity to flow from the positive end of the battery to the negative end;
• The globe only works when one wire is in contact with the casings and another with the base;