Read the following carefully to answer.
1. When an immersion water heater is dipped inside a bucket of water, the of the water heats up first. The heat then travels to the rest of the water below through . Since the immersion rod is a metal, the from the metal which is is conducted to the water which is . The handle of the immersion heater is made of plastic because it is a conductor of heat.
2. Air is an insulator because .