2. Rays

About this Lecture

Lecture

In this mini-lecture, we explore the concept of rays, focusing in particular on: (i) familiar notions of light rays, such as rays of sunlight and laser pointers; (ii) the developments of the ray concept made by Arabic scientists, Ibn Sahl and Ibn al Haytham, in the tenth and eleventh centuries; (iii) the camera obscura and the green flash; (iv) a general understanding that when light propagates through substances it can refract, reflect, scatter, and absorb; (v) mirrors and reflective surfaces in art; (vi) understanding why light reflects from metal surfaces; (vii) using a ray simulator (Rick Tu, https://ricktu288.github.io/ray-optics/, 2021) to play around with rays, mirrors, point sources, and virtual sources; and (ix) three exercises on rays for students to try on their own.

Course

In this course Professor Charles Adams (Durham University) gives an introduction to optics for GCSE students. In the first mini-lecture, we explore the big picture of optics, defining it broadly as the science of light, seeking to understand light as a wave, and concluding with some impacts and applications of optics. In the second mini-lecture, we explore the concept of light rays, their historical developments dating back to the tenth century, and some of their properties such as refraction, reflection, and absorption. In the third mini-lecture, we delve deeper into refraction and reflection as we introduce the concept of the index of refraction of optical mediums, look at examples, and play around with some simulators to mimic these effects. The fourth mini-lecture turns towards lenses, including important historical developments, how a lens works, and the power of a lens. The fifth mini-lecture explores imaging, addressing the question of how to make a better lens, the limitations of the lens, and how our improved understanding of optics and lenses led to advances in areas such as microscopy and medicine.

Lecturer

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).