Sunburn is caused by UV radiation, either from the sun or from artificial sources, such as tanning lamps, welding arcs, or ultraviolet germicidal irradiation. It is a reaction of the body to direct DNA damage from UVB light. This damage is mainly the formation of a thymine dimer.xcessive UV radiation is the leading cause of primarily non-malignant skin tumors. Sunscreen is widely agreed to prevent sunburn and some types of skin cancer. Clothing, including hats, is considered the preferred skin protection method.
A protractor is used to measure angles. When surveying a theodolite is used. There are a number of tools on the market that perform angle measurement. A <b>protractor</b> is used to measure angles.<br />When surveying a <b>theodolite</b> is used.<br />There are a number of tools on the market that perform angle measurement. Minor edit?
3.4 The instrument has both British and metric scales and is provided with devices to measure internal depths and both inside and outside diameters. The jaws c and d are arranged to measure an outside diameter, jaws e and f to measure an inside diameter, and the blade g to measure an internal depth. The knurled wheel W is used for convenient adjustment of the movable jaw and the latch L to lock the jaw in position.