Problem 3
Light travels from glass of refractive index 1.5 into air. Find the critical angle and condition for total internal reflection. Use the stated ideal model: quantities are constant or vary only as specified, with no extra drag, losses, or external influences. State a sign convention, keep units consistent, and use a classical approximation only where appropriate. (a) Set up the governing equation from a fundamental law. (b) Solve for the requested quantity under the stated conditions. (c) Check the result using a suitable limit, sign, or unit test, and report both the expression and its physical meaning.
problems.proof.stepOf
problems.proof.analysis
Apply the fundamental law to the correct system and interval. A conservation law is valid only when the assumptions ensure its corresponding conservation condition.
problems.proof.pitfall. A critical angle exists only for light going from higher to lower refractive index; measure angles from the normal.