RADIANT ENERGY

Radiation There is much public concern about radiation. In an opinion poll, the public was asked to rank risks of a number of hazards. Radiation was # 1 based on the data. The least hazardous was more likely to cause injury or death. Sometimes, the fear of radiation gets out of proportion. For example, a person may not want an x-ray to be used as the primary source for an internal examination.

Radiation is a valuable research tool. However, although it is beneficial when utilized properly, it can be extremely dangerous when it is misused. For example, over exposure of UV rays at the beach is harmful and unhealthy to one’s skin and can cause several types of cancer. This is why standards for exposure and release must be established and followed.

Radiation is mostly natural in 37% cosmic rays and terrestrial environment, 28% in building materials, 16% in food and water, 12% in medical usage, 4% in color television, 2% in long distance airplane flights, and 1% in living near nuclear power plants (under normal operating conditions).

WAVES Light travels through space in waves and is a form of radiant energy. Radiant energy is electromagnetic energy that travels in transverse waves. Light waves are electromagnetic waves and light is a form of electromagnetic radiation.

FORMS OF ELETROMAGNETIC RADIATION 1. x-rays 2.radio waves 3. gamma rays

Parts of a Wave

Characteristics of Waves Amplitude: height of the wave measured from the origin to its crest, or peak (the brightness of the light depends on the amplitude of the light wave)

Wavelength and Frequency Wavelength (λ): distance between successive crests of the wave (It is the distance that the wave travels as it completes one full cycle of upward and downward motion.) Frequency (ν): tells how fast the wave oscillates up and down

Speed of Light Speed: light moves through space at a constant speed of 3.00 x 10 8 meters per second (m/s) which is the speed of light (speed of light is about 186,282 miles per second)

Since light moves at a constant speed, there is a relationship between its wavelength and its frequency. The shorter the distance between the crests, the faster the wave oscillates up and down. Therefore, the shorter the wavelength, the greater the frequency and the longer the wavelength, the lower the frequency. This is an inversely proportional relationship.

Electromagnetic Spectrum The electromagnetic spectrum is invisible to the human eye. There is only a very small portion of the total electromagnetic spectrum that your eyes can see. Visible light includes the colors of the rainbow; ROYGBIV. The different colors have different frequencies. Violet has the shortest wavelength and highest frequency. Red has the longest wavelength and lowest frequency.

Electromagnetic Spectrum