UV Light

UV Light


The main objective of this science model is to know about the protection which is offered by sunglasses and sunscreens to the ultraviolet light. The experiment helps you in understanding how to block the ultraviolet light. The experiments here are compared and quantified to the effectiveness of the sunscreens with various strengths, ages, brands under different set of conditions.


Ultraviolet light sensitive disks are the ones that are used in testing the amount of light able to make way through the sunscreen or some protective surface. When these disks absorb the ultraviolet light, color change takes place to red or blue based upon the kind of disk selected. Both physics, as well as chemistry based analyses, are been performed. In the physics based analysis, the blocking of ultraviolet light rays is measured usually by performing the color related experiments on a computer.

In particular, the images of control, as well as the test groups of the disks are taken out with the help of digital camera. The disks are exposed to a known amount of UV light. On the exposure, disks change the colors. The change in the color, which is said to be proportional to amount of the absorption of UV light, is found out by measuring saturation of color. Later quantitative experiments are performed for large numbers of images and the results are said to be evaluated based on the composition of chemicals present in sunscreen.


As per the results obtained from the experiment, the Combinations of various ingredients and the SPF has a significant effect based on efficiency of the sunscreen.

The Standard protection factor of any sunscreen and the chemical composition are two most important considerations while deciding as to which sunscreen can be used in different environmental conditions to block the UV light rays.4

Practise This Question

The acceleration of a body due to the attraction of the earth (radius R) at a distance 2R from the surface of the earth is (g = acceleration due to gravity at the surface of the earth)