Rheostat, 100 Ω, 1.75 A

An enclosed slide resistor whose resistance wire is wound on a stable ceramic tube and which carries three safety sockets, allowing use as either a variable resistor or a voltage divider. It can be overloaded by 100% for short periods (up to 4 minutes) and has a maximum power rating of 320 W. In physics lessons it lets pupils regulate current and voltage in circuits — for example demonstrating Ohm's law, voltage division and power dissipation — adjusting the resistance steplessly to see how the changes affect the circuit and reinforcing their grasp of the link between current, voltage and resistance.