Episode Details

So today's question is: how do you steer something moving at 300,000 kilometres every second? It turns out light only lets you do two things to it, bounce it or slow it down, and by the end you'll know the exact rule for each.

Two rules, one invisible line. Reflection: the angle of incidence equals the angle of reflection, measured in degrees from the normal. Refraction: when light crosses into a new material it changes speed, measured in km/s, and that change of speed bends it toward or away from the normal, unless it arrives straight along the normal. The listener can now explain the Moon mirror, a periscope, and the lens in their own eye.

Sources:

• https://www.schoolphysics.co.uk/age11-14/Light/text/Refraction_/index.html
• https://eclipse.gsfc.nasa.gov/SEhelp/ApolloLaser.html

Source: Episode 5 - Physics Level 8, Bouncing and Bending Light (5/17)
Style: Exam prep
Length: 1131 words, 7 min target
Generated: 2026-10-25