How do you make a light 240volt work with 12volt switch?

To control a 240-volt light with a 12-volt switch, you can use a relay. The 12-volt switch activates the relay, which acts as an electrically operated switch that can handle the higher voltage and current of the 240-volt circuit. Ensure the relay is rated for the 240 volts and the current required by the light. Always follow safety protocols and consult a qualified electrician if unsure.