Answer:

1. The microwave oven transforms electrical energy into microwaves, a type of electromagnetic energy. The microwaves are transformed into thermal energy as they are absorbed by the popcorn kernels. When the kernels become hot enough they pop.

2. The energy transformations in a firecracker are chemical energy to light, thermal, and sound energy.

3. When you ride a bicycle, several things happen that require energy and it's transformation. You pedaling the bike is transforming chemical energy, supplied by the breakdown of the food you eat, into mechanical energy to turn the pedals. The chemical energy is potential and the mechanical energy is kinetic.

4. A battery is a device that stores chemical energy and converts it to electrical energy. The chemical reactions in a battery involve the flow of electrons from one material (electrode) to another, through an external circuit. The flow of electrons provides an electric current that can be used to do work.