In 1801 Ritter conducted experiments with silver chloride and a prism. He projected a beam of sunlight through the prism, which split the beam into the colors of the spectrum. He them put chloride in each color to see the outcome. The red caused a small change while the deep violet darkened the chloride. Ritter placed chloride in the lightless area just beyond the violet and it darkened as it were in a smoky fire. The was evidence of another wave form just barely higher than the violet of visible light. It is now known as ultraviolet or UV light.

Man-Made UV rays:

UV rays can be made artificially by passing an electric current through a gas or vapor, such as mercury vapor.

The Effects of Ultraviolet on the Skin –

UV waves injure cells in the epidermis (outer layer) by diffusing into the inner layer and causing an enlargement of vessels. Blisters can occur due to too much exposure. If there is overexposure, blisters can leave scars or can cause skin cancer

UV rays are used in:

Ultraviolet waves are effective in killing bacteria and viruses. Hospitals use germicidal lamps that produce these waves to sterilize equipment, water and air in operating rooms. It is also used to treat acne and psoriasis.

The Food and Drug industry uses germicidal lamps to disinfect various types of products and their containers. The main use of ultraviolet is in the manufacturing integrated circuits.
Scientists learn about the make up and energy levels of atoms by studying UV rays. Experts also learn abut distant stars and galaxies by analyzing the UV rays that are given off. Artificial sources of ultraviolet light are often used to stimulate the effects of solar ultraviolet radiation in the study of the deterioration of materials on exposure to sunlight

Consumer Goods:
Ultraviolet waves are used to identify materials by the glow or fluorescence under them. They are used to make black lights. May food and drug companies use germicidal lamps to disinfect various types of products, and their containers.

UV from Space:

The sun and lightening are celestial bodies that emit ultraviolet waves. Electrical sparks in the air causes an emission of UV. Ultraviolet light is emitted by the sun. Ultraviolet radiation is related with hot objects. Examples are stars with surface temperature in range of 50,000 to 1000,000 K and hot gas clouds found between the stars.

Dangers associated with Ultraviolet Waves:

Overexposure to these ultraviolet waves can cause painful eye irritation, sunburns and skin cancer. These waves can also cause the destruction of plants and the breakdown of the ozone layer. Ultraviolet exposure can also damage and kill plants. Some photobiological effects include cell mutation, interference in the division of cells and an increased rate of respiration.


High quality sunglasses protect the eyes from UV rays, and sunscreen to protect the skin from sunburn. Other devices include UV detectors, phototubes, photovoltaic cells, and radiometric devices.

Detecting Ultraviolet Rays:

We use rockets and a series of orbiting satellites to detect UV rays that come from space.

Fun Facts:

Experiments indicate that bees, birds, butterflies and other insects can see ultraviolet light. The reflection of UV rays off wings help insects identify mates.
Birds have the ability to see ultraviolet light as well as the primary colors. Research indicates that this ability plays a role in bird’s reproductive habits, as they prefer mates that detect ultraviolet light.
Ultraviolet rays cause chemical reactions in plants. If they are overexposed to it, it could kill them.