An immersion heater used to boil water for a single cup of tea plugs into a 120V outlet and is rated at 300W. What is the resistance of the heater?
Suppose your super0sive, super-insulated tea mug contains 400g of water at a temp of 18 degrees Celsius. How long will this heater take to bring the water to a boil? Ignore the energy needed to raise the temperature of the mug and the heater itself.