You have a layer of glass with a refractive index of 1.5 and the glass is surrounded by air. A light ray shines into the glass and Total Internal Reflection occurs at the glass-air boundary. What is the critical angle?
This question tests your knowledge of Snell's law, Total Internal Reflection (TIR) and the fact that the refractive index of air is 1 (which should be memorised as it is in the exam). The critical angle is the angle at which TIR occurs, which can be calculated with the equation from Snell's law that relates angle of incident and refraction with the two refractive indices. The trick here is to use the angle of refraction as 90 degrees to apply the condition of TIR.
KC
Related Physics A Level answers
All answers ▸Derive an expression for the centripetal acceleration of a body in uniform circular motion.
Derive an expression for wave speed in terms of wavelength and frequency.
How to we work out the speed of an object at a certain point in its trajectory?
If a ball of mass 5kg is dropped from rest, how far will it travel in the 3 seconds after it reaches 150m from it's original position? Write down the change in it's total energy after the 3 seconds. (ignoring air resistance)