Sunlight and Solar Energy

Find out more about sunlight, the effects of ultraviolet light, and experiment with ultra violet light.

Trivia Questions

1. Can you get a sun burn or a tan by sitting next to a fluorescent light?
2. What is black light?

Find the answers to these kids science questions.

Continue reading "Sunlight and Solar Energy"

The energy produced by the sun is electromagnetic radiation with many different wavelengths. Only a small portion of these wavelengths are visible to the human eye. These visible wavelengths are seen as colors of the rainbow depending on the wavelength. Red has the longest visible wavelength and violet has the shortest visible wavelength. When all the waves are seen together, they make white light.

Waves longer than those seen as red, are called infrared.  Waves shorter than violet are called ultraviolet.  Ultraviolet light comes in different lengths too.

Short wave ultraviolet light is used to kill bacteria, hasten chemical reactions and can be used to identify some fluorescent minerals. Unlike long wave UV, the short wave UV cannot pass through ordinary glass nor most plastics.

Properties of Ultra-Violet Light

Ultra-violet light (UV light) has shorter wavelengths than violet light. It can not be seen by the human eye. Some animals, including birds, reptiles, and insects such as bees, can see into the near ultraviolet. Many fruits, flowers, and seeds stand out more strongly from the background in ultraviolet wavelengths as compared to human color vision. Many birds have patterns in their plumage that are invisible at usual wavelengths but seen in ultraviolet.

Although invisible to humans, UV light has many of the properties of normal sunlight. UV light can cause sunburn, hurt the eyes and even cause discoloration of material dyed with organic dyes.

Some UV light is absorbed by the ozone in atmosphere, but some of the UV light still reaches Earth and can cause damage to the skin.

UV light comes in different wavelengths just like visible light. The most common wavelengths are called UVA and UVB. UVA is the same strength all year around, all day long, at all locations between the poles, and easily goes through most glass and plastic. UVB is stronger between 10am and 2pm, during the summer months, closer to the equator and does not go through most glass and plastic.

Most UVB is absorbed by the ozone layer in the earth's atmosphere. 99% of the ultraviolet radiation that reaches the Earth's surface is UVA.

Effects of Ultra-Violet Light

When bare skin is exposed to sunlight, most skin will either burn or tan. UV light wavelengths are short enough to break the chemical bonds in skin tissue. With prolonged exposure, skin may wrinkle or skin cancer may appear.  Burning or tanning are skin's natural response when skin cells are exposed to UV light.

Websites with information on Sunlight and Energy

• Electromagnetic Spectrum
• Light Energy

Word Definitions

• Ultra - Latin for beyond
• Electromagnetic Spectrum - the distribution of electromagnetic radiation, like sunlight, according to energy shown as waves.
• Wave Frequency - the number of times a wave crest passes a point in a second.
• Wavelength - the distance between two successive wave crests.

Trivia Answers

1) Can you get a sun burn or a tan by sitting next to a fluorescent light?

• No.

2) What is black light?

• Black light is a type of light in the near ultraviolet range, just short of visible light. Fluorescents can absorb this ultraviolet radiation and emit light in the visible region. The darker the surroundings the brighter this emitted light appears to be. Extended exposure to black light can be harmful unless protective eye wear is used.

Notes to Parents:

1. Every parent must use their own judgment in choosing which activities are safe for their own children.  While Science Kids at Home makes every effort to provide activity ideas that are safe and fun for children it is your responsibility to choose the activities that are safe in your own home.
2. Science Kids at Home has checked the external web links on this page that we created.  We believe these links provide interesting information that is appropriate for kids.  However, the internet is a constantly changing place and these links may not work or the external web site may have changed.  We also have no control over the "Ads by Google" links, but these should be related to kids science and crafts.  You are responsible for supervising your own children.  If you ever find a link that you feel is inappropriate, please let us know.

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