EGEE 102
Energy Conservation for Environmental Protection

Forms of Energy, page 2 of 2


Electrical Energy:

  • Energy created through the movement of electrons among the atoms of matter.
  • Although electricity is seldom used directly, it is one of the most useful and versatile forms of energy. Following are some examples. When electricity is:
    • put into a toaster, it can be converted to heat;
    • put into a stereo, it is converted into sound;
    • put into an electric bulb, it converts into light;
    • put into a motor, it converts into motion or movement (mechanical energy).
  • Due to its versatility, electricity is in high demand; in the US, about 40% of the total primary energy used is converted into electricity for various uses.

Remember This!

All matter is made up of atoms, and atoms are made up of smaller particles called protons (which have positive charge), neutrons (which have neutral charge), and electrons (which are negatively charged).

  • The electrons orbit around the nucleus (which contains protons and neutrons), just like the planets orbit the sun.
  • Certain metals have electrons that are only loosely attached to their atoms, so they can be easily made to move from one atom to another if an electric field is applied to them.
  • When those electrons move among the atoms of matter, a current of electricity is created.

Nuclear Energy:

  • Energy produced when reactions occur in an atom, resulting in some type of structural change in the nuclei.
  • Fusion occurs when two small nuclei join together to create one large nucleus or particle, and during this process, energy is released in the form of light and heat. An example is in the Sun: hydrogen nuclei fuse (combine) together to make helium nuclei, which release energy.
  • Fission occurs when the nucleus of one big atom splits into two new atoms, and during this process, a tremendous amount of energy is released in the form of light and heat. An example is in a nuclear reactor or the interior of the earth: uranium nuclei split apart, causing energy to be released.

Did You Know?

In both fusion and fission, some of the matter making up the nuclei is converted into energy, represented by the famous equation:

E=mc 2 Energy=Mass× ( Speed of Light ) 2
  • This formula indicates that energy intrinsically stored in matter at rest equals its mass times the speed of light squared. When matter is destroyed, the energy stored is released.
  • This equation suggests that an incredibly huge amount of energy is released when a small amount of matter is converted to energy.


  • Energy radiated or transmitted in the form of rays, waves, or particles. Some examples include:
    • visible light that can be seen by naked eye;
    • infrared radiation;
    • ultraviolet radiation (UV) that cannot be seen with the naked eye;
    • long wave radiation, such as TV waves and radio waves;
    • very short waves, such as x-rays and gamma rays.

Even things that we encounter in our every day life contain some radioactive material, either natural or man-made. Smoke detectors, compact fluorescent bulbs, some watches and granite countertops can emit some nuclear radiation. Even plane travel at high altitudes cause exposure from cosmic rays.

  • Electromagnetic Radiation
    • Energy from the sun comes to the earth in the form of Electromagnetic radiation, which is a type of energy that oscillates (side to side) and is coupled with electric and magnetic fields that travel freely through space.
    • Electromagnetic radiation is composed of photons or particles of light, which are sometimes referred to as packets of energy.
    • Photons, like all particles, have properties of waves.

Photons make the world a brighter place!

Photons are created when electrons jump to lower energy levels in atoms, and are absorbed when electrons jump to higher levels. Photons are also created when a charged particle, such as an electron or proton, is accelerated. An example of this phenomenon is a radio transmitter antenna that generates radio waves.

  • Electromagnetic Spectrum
    • The “Electromagnetic spectrum“ is a representation of the wide range of wavelengths of electromagnetic radiation.
    • Photons are associated with visible light, which accounts for only a very limited part of the electromagnetic spectrum.
    • A great discovery of the nineteenth century was that radio waves, x-rays, and gamma-rays are just forms of light, and that light is electromagnetic waves.

Please watch the following 5:00 video about the electromagnetic spectrum:

Click for Transcript of Tour of the EMS 01 - Introduction

Something surrounds you. Bombards you. Some of which you can't see, touch, or even feel. Every day, everywhere you go. It is odorless and tasteless. Yet you use it and depend on it every hour of every day. Without it the world you know could not exist. What is it? Electromagnetic radiation. These waves spread across the spectrum from very short gamma rays to x-rays, ultraviolet rays, visible light rays, even longer infrared light waves, microwaves, to radio waves which can measure longer than a mountain range. This spectrum is the foundation of the information age and of our modern world. Your radio, remote control, text message, television, microwave oven, even a doctor's x-ray, all depend on waves within the electromagnetic spectrum.

Electromagnetic waves, or EM waves, are similar to ocean waves in that both are energy waves. They transmit energy. EM waves are produced by the vibration of charged particles and have electrical and magnetic properties. But unlike ocean waves that require water, EM waves travel through the vacuum of space at the constant speed of light. EM waves have crests and troughs like ocean waves. The distance between crests is the wavelength. While some EM wavelengths are very long and are measured in meters, many are tiny and are measured in billionths of a meter, nanometers. The number of these crests that pass a given point within one second is described as the frequency of the wave. One wave or cycle per second is called a Hertz. Long EM waves, such as radio waves, have the lowest frequency and carry less energy. Adding energy increases the frequency of the wave and makes the wavelength shorter. Gamma rays are the shortest, highest energy waves in the spectrum. So, as you sit watching TV, not only are there visible light waves from the TV striking your eyes, but also radio waves transmitting from a nearby station; and microwaves carrying cellphone calls and text messages; and waves from your neighbors Wi-Fi and GPS units in the cars driving by. There's a chaos of waves from all across the spectrum passing through your room right now.

With all of these waves around you, how can you possibly watch your TV show. Similar to tuning a radio to a specific radio station, our eyes are tuned to a specific region of the EM spectrum and can detect energy with wavelengths from 400 to 700 nanometers. The visible light region of the spectrum. Objects appear to have color because EM waves interact with their molecules. Some wavelengths in the visible spectrum are reflected and other wavelengths are absorbed. This leaf looks green because EM waves interact with the chlorophyl molecules. Waves between 492 and 577 nanometers in length are reflected and our eye interprets this as the leaf being green. Our eyes see the leaf as green but cannot tell us anything about how the leaf reflects ultraviolet, microwave, or infrared waves.

To learn more about the world around us, scientists and engineers have devised ways to enable us to see beyond that sliver of the EM spectrum called visible light. Data from multiple wavelengths help scientists study all kinds of amazing phenomena on Earth from seasonal change to specific habitats. Everything around us emits, reflects, and absorbs EM radiation differently based on it's composition. A graph across the EM spectrum is called the spectral signature. Characteristic patterns like fingerprints within the spectra allow scientists to determine an object's chemical composition and to determine such physical properties as temperature and density.

NASA's Spitzer space telescope observed the presence of water and organic molecules in a galaxy 3.2 billion light years away. Viewing our sun in multiple wavelengths with the SOHO satellite allows scientists to study and understand sunspots that are associated with solar flares and eruptions that are harmful to satellites, astronauts and communications here on Earth.

We are constantly learning more about our world and universe by taking advantage of the unique information contained in the different waves across the EM spectrum.

As depicted in the image above, the lower the energy, the longer the wavelength and lower the frequency, and vice versa.

The reason that sunlight can hurt your skin or your eyes is because it contains "ultraviolet light," which consists of high energy photons. These photons have short wavelength and high frequency, and pack enough energy in each photon to cause physical damage to your skin if they get past the outer layer of skin or the lens in your eye.

Radio waves, and the radiant heat you feel at a distance from a campfire, for example, are also forms of electromagnetic radiation, or light, except that they consist of low energy photons (long wavelength and high frequencies - in the infrared band and lower) that your eyes can't perceive. This was a great discovery of the nineteenth century - that radio waves, x-rays, and gamma-rays are just forms of light, and that light is electromagnetic waves.

About 20% of the electricity used in the US is used to produce visible light for lighting purposes.