You are not currently logged in. Please create an account or sign in to view the full course.

Optics II

3. Polarisation: the Dog, the Mosquito, and Element 53

This is the course trailer. Please create an account or sign in to view this lecture.

  • Description
  • Cite

About this Lecture


In this mini-lecture, we introduce the concept of polarisation. As we move throughout the mini-lecture, we consider: (i) how light has two polarisations: vertical and horizontal; (ii) how a polarising filter on, say, a camera can affect the colour and brightness of an image; (iii) historical context such as Etienne Malus’ discovery in 1808 when he found that a quartz crystal transmits different amounts of light depending on its orientation; (iii) a demonstration of how polaroid sheets work; (iv) how polaroid sheets were invented, a story involving a dog, a mosquito, element 53, and the resulting chemical compound called Herapathite; (v) a demonstration that compares white light propagating through a polaroid filter with white light propagating through a jar of sugar syrup and viewed from a polarising filter, where we see that the filter produces spots of different coloured light in the latter scenario; (vi) a demonstration of laser light propagating through sugar syrup and viewed from a polarising filter to highlight the helicoidal nature of the light; (vii) light as a helix with left and right circular polarisation, which is equivalent to the picture of light with vertical and horizontal polarisation; (viii) some implications of the optical rotation of polarisation of light in sugar, including developments in food science and the discovery of chiral chemistry; and (ix) an exercise on polarisation.


In this course, Professor Charles Adams (Durham University) follows from his Optics I course and provides a more advanced account of optics. In the first mini-lecture, we discuss lenses, this time going into more depth by first deriving the thin lens equation and then looking at the additive property of the optical power of lenses. In the second mini-lecture, we revisit refraction, derive the Law of Ibn Sahl (also known as Snell’s Law), and introduce the concepts of the critical angle and total internal reflection. The third mini-lecture introduces the polarisation of light, including historical context on the development of polaroid sheets, as well as two demonstrations that involve light propagating through sugar syrup and a polaroid sheet. The fourth mini-lecture delves into the quantum aspects of light, introducing topics such as wave-particle duality, quantum technology, Young’s double slit experiment, the Heisenberg microscope, and complementarity.


Charles Adams is a Professor in the Department of Physics at Durham University. His principal research interests are in experimental quantum optics, in particular light-matter interactions in strongly-interacting atomic systems. He was the 2014 recipient of the Joseph Thomson Medal, awarded by the Institute of Physics (IOP) to those who have made distinguished contributions to atomic or molecular physics. In 2020, he was awarded the Holweck Prize by the French Physical Society and the IOP for pioneering work in quantum optics. Professor Adams is also a co-author of the optics textbook Optics f2f: From Fourier to Fresnel (2018).

Cite this Lecture

APA style

Adams, C. (2022, January 12). Optics II - Polarisation: the Dog, the Mosquito, and Element 53 [Video]. MASSOLIT.

MLA style

Adams, Charles. "Optics II – Polarisation: the Dog, the Mosquito, and Element 53." MASSOLIT, uploaded by MASSOLIT, 12 Jan 2022,

Image Credits

Get instant access to over 4,000 lectures