IB Physics HL IA

Physics Internal Assessment

-Specific Rotation-

Overview

Light has been a source of inspiration for me since I was very young. It is so ubiquitous that it seems very familiar to us. However, while seeming so friendly to us, light itself is invisible and thus is very mysterious and interesting. Therefore, when I first heard in my physics class that light can be polarised and the polarised light can be rotated by a substance, it grabbed my attention at once. It was so fascinating that an invisible thing can be manipulated and affected by a scientific phenomenon. However, since the whole phenomenon was invisible due to light’s own characteristic, I was willing to observe this mysterious rotation of polarised light and further investigate what affects these phenomenon. This led me to my research question which revolves around; What are the factors affecting the angle of rotation of light passing through an optical active substance?

Background Information

Polarisation and polarizer

Usually, monochromatic light (visible light) is a transverse wave in which an electric field oscillates in all possible planes perpendicular to the line of propagation. This light is called unpolarised. A polariser polarizes this light which means that the wave oscillates in only one plane as it goes through a special type of slit that only allows light propagating on one plane.