Some forms of energy can be converted to other forms. For example, solar panels are used to capture light energy from the sun and convert it to electricity Green plants undergo photosynthesis to convert light energy into chemical energy in the form of food. The mechanical energy of a waterfall can be converted to electromagnetic energy in a generator.
Generators convert other types of mechanical energy into electromagnetic energy.
The bicycle generators turn with the bicycle tires and cause the light to turn on. Many times it takes a whole series of energy conversions to do a certain job. For example, just to get the energy to make a piece of toast, there are several energy conversions involved. Chemical energy stored in coal is released as heat energy when the coal is burned. The heat energy is used to produce steam and is changed into mechanical energy in a generator.