This energy travels as electromagnetic waves at about the speed of light, which is 670,616,629 miles per hour,1 or 300 million meters per second. 2 However, the electrons themselves within the wave move more slowly. This concept is known as drift velocity.

It is better to talk about the consumption or extraction of energy resources, for example coal, oil, or wind, than consumption of energy itself. A speeding bullet has a measurable amount of energy associated with it; this is known as kinetic energy.

Most of the energy is transferred as thermal energy which is not useful and only some of the energy is transferred as light.

Some forms of energy are more useful than others. Using energy always makes it less useful, even though no energy is actually destroyed. Kinetic energy and electricity are the most useful forms. These are “high-quality” because they can be transformed almost completely into any other type of energy.

Examples of Energy Transformations:

• A toaster transforms electrical energy into thermal energy.
• A blender transforms electrical energy into mechanical energy.
• The sun transforms nuclear energy into ultraviolet, infrared, and gamma energy all forms of electromagnetic energy.

Examples of transformation of energy in daily life activities

1. A toaster transforms electrical energy into thermal energy.
2. A blender transforms electrical energy into mechanical energy.
3. The sun transforms nuclear energy into ultraviolet, infrared, and gamma energy all forms of electromagnetic energy.

electrical energy

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.

heat

kinetic energy

photosynthesis

When the match is struck, it burns and the chemical energy in it produces heat energy and light energy. Candles also possess a lot of chemical energy. So does petrol. Some substances absorb heat energy and change it into chemical energy.

Lighting a match and letting is burn is an example of a chemical change. Chemical reactions cause chemical changes. In a chemical reaction two or more substances, called the reactants, form different substances called products.

Hair dryers use heating element and motor-driven fan to convert electric energy into convective heat.

1.8 Power is a measure of energy transfer rate. It is useful to talk about the rate at which energy is transferred from one system to another (energy per time). This rate is called power. One joule of energy transferred in one second is called a Watt (i.e., 1 joule/second = 1 Watt).

Heat can be transferred in three ways: by conduction, by convection, and by radiation.

1. Conduction is the transfer of energy from one molecule to another by direct contact.
2. Convection is the movement of heat by a fluid such as water or air.
3. Radiation is the transfer of heat by electromagnetic waves.

Energy is transferred out of hotter regions or objects and into colder ones by the processes of conduction, convection, and radiation. By the end of grade 12. Conservation of energy means that the total change of energy in any system is always equal to the total energy transferred into or out of the system.