Category: Physics

The Leibniz integral rule in electrodynamics

I have been slowly working through David Griffith’s widely-used textbook, Introduction to Electrodynamics. It is known for having a large number of reasonably difficult exercises, which are instrumental in conveying some concepts not directly addressed in the main text. I found an elegant shortcut to one of the questions, which was not noted in the solution manual. The shortcut involves (ab)using a very versatile, if slightly overlooked theorem in calculus – the Leibniz integral rule. I will briefly discuss this, before working through the problem.


The Cambridge Natural Sciences Interview

In December 2015, just after finishing my IB exams, I went to Cambridge for my (Physical) Natural Sciences Interview. The interview has a reputation for being incredibly demanding and intense, and you’ve probably seen on the internet some of the ‘crazy’ questions that people get asked. Although it is definitely stressful, the Cambridge interview is almost purely academic (and quite reasonable). So without further ado, these are the questions I was asked, along with my thoughts at the time and the interviewer’s reactions.