Physics

__** PHYSICS **__

**INTRODUCTION** For physics, we will take 5 different samples of water including Westlake water, distilled water, bathroom water, drinking water (from water dispenser) and UNIS pond water (the one in front of Biology room). We will then measure the refractive index & the density of these water samples and compare them. Since the refractivec index of water can tell the level of pollution of the water, by measuring and comparing, we can draw out a conclusion on how polluted Westlake water is compared to other samples.

__ Refractive index __ The refraction is defined as a change in direction of light caused by a change in its speed when light passes from a medium of a particular optical density into another medium with a different optical density. The change in the speed of light causes the wave to deviate from the normal. The refractive index is the amount of which light bends when it enter a medium. Different materials/mediums have different refractive index. The refractive index of pure water is 1.33 and the refractive index of air is 1.00. The refractive index can be calculated using the following formula: n= sin(incident angle) / sin(refractive angle) in which n is the refractive index __ Link to pollution __ In pure water, the refractive index is approximately 1.33. If the water is polluted and includes impurities, the water will be denser. Light bends / refracts as it travels from one medium to another with different density. The denser the second medium is, the larger the refractive index will be
 * DENSITY, REFRACTIVE INDEX & POLLUTION **


 * EQUIPMENT **
 * Equipment || Quantity ||
 * Protractor || 2 ||
 * 500ml beaker || 5 ||
 * 30cm ruler || 2 ||
 * Power pack || 1 ||
 * Ray box || 1 ||
 * Reactangular box || 1 ||
 * METHOD **