Electricity & Megnetism

Ultraviolet (UV) radiation

The Sun is the biggest emitter of ultraviolet radiation. Thanks to the ozone layer, this radiation reaches the Earth in small amounts, but it still continues

We know that all electromagnetic waves, regardless of their frequency, carry energy. However, the energy carried by an electromagnetic wave depends on this frequency, that is, the higher the frequency, the greater the energy that the electromagnetic wave carries. We have to be aware of the fact that electromagnetic waves also undergo reflection, refraction and diffraction.

As we studied the electromagnetic spectrum, we saw that the visible spectrum is the part of the electromagnetic spectrum that can be perceived by our vision system. Thus, we can say that visible light comprises radiation with a wavelength between 380 nm and 750 nm. This radiation is important as it is used in the mechanism of vision.

the ultraviolet radiation is defined as all radiation with a wavelength shorter than 400nm, being very harmful to living beings. Our atmosphere filters most of the radiation the Sun emits, allowing life on Earth. The ozone layer is responsible for absorbing this radiation, but the holes in it present a serious risk to everyone.

Living beings can easily withstand small doses of ultraviolet radiation, as damaged cells can regenerate. With the increased incidence of ultraviolet rays, the damage happens at a faster rate than it can be repaired, causing skin cancer, cataracts and a deficiency in the immune system. The effect of ultraviolet radiation is felt in animals as well as in plants.

Ultraviolet radiation is also reflected by many materials, and even when we are not in direct sunlight, we can easily get burned. Beach sand, for example, reflects 20% of the incident UV radiation. Another example is snow, which can reflect about 90%. For this reason, we sometimes see skiers and climbers with severe burns. In contrast, many substances, such as glass, absorb ultraviolet radiation.

For adequate protection from the action of UV rays, we can use specific sunscreens for this radiation. These protectors use chemicals that absorb UV radiation, not allowing the skin to be affected. To be effective, filters and blockers must absorb UVB radiation, which is the most harmful.

With the increase in the hole in the ozone layer, there is an increase in the amount of ultraviolet rays that reach the Earth’s surface, making the use of sunscreens indispensable.

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