Why a Straw Looks Bent in Water
📖 Why a Straw Looks Bent in Water
Refraction occurs because different media have different optical densities, which affects how fast light (or any wave) can travel through them. When a wave front hits a boundary at an angle, one side of the wave hits the new medium first and slows down, while the other side is still in the old medium at its original sp
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🧠 Memory Aid
Refraction direction: "Slow to Fast — bend away from normal. Fast to Slow — bend toward normal."
Or remember it with a speed analogy: entering a denser medium is like a car going from tarmac into mud. The car slows and turns toward the mud (toward the normal). Coming back out of mud onto tarmac, it speeds up and swings away.
Critical angle conditions — the "DANG" rule:
- Denser medium (light must be in the denser material)
- Angle is greater than critical angle
- No refraction occurs
- Goes back by total reflection
Now try it yourself
Quiz · Question 1 of 15
According to the law of reflection, the angle of incidence is:
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This topic in real past papers
Every real exam question we've found on reflection & refraction, with a full worked answer.