UV Light and Sunglasses

Introduction

Sunglasses have lenses that are darkened or colored to reduce the brightness of light entering the eye. Some people wear sunglasses because bright sunlight is uncomfortable. Other people wear sunglasses as a fashion accessory. Healthcare professionals recommend all people wear sunglasses to reduce the adverse effects of ultraviolet radiation on the eyes.

The UV band is broken into three types referred to as UVA (with wavelengths of 320 to 400 nm), UVB (280 to 320 nm), and UVC (200 to 280 nm). The most harmful of these three, UVC light, is absorbed by oxygen and ozone in the atmosphere and does not reach the Earth’s surface. The ozone layer absorbs much, but not all, incoming UVB light. Some UVB light reaches the surface of Earth. UVA light is not affected by the ozone layer, and most reaches the surface of Earth. UVB light is commonly associated with sunburns, cataracts, and skin cancer. UVA light, while responsible for suntans, is also a cause of premature aging of the skin and some types of skin cancer.

In this experiment, you will conduct a study on the various types of sunglasses, and the levels of UVB light that pass through their lenses.

Objectives

In this experiment, you will

• Use a UVB Sensor to measure UVB light.
• Determine the amount of UVB light allowed through an assortment of sunglasses.
• Determine whether the UVB-blocking abilities of sunglasses change with lens tint.