Refraction and Refractive Index

Lab Brief #2

🎯 Your mission

Run the experiment. Find out what really happens.

⚡ The twist

Speed isn't the same as force. Don't mix them up.

What you'll learn

Light bends when it enters a medium where its speed differs. Going into a denser medium it slows and bends towards the normal. The refractive index is the ratio of speeds, and it is why a straw looks broken at the water line.

Key words

refractive index
The ratio of the speed of light in a vacuum to its speed in a medium.
angle of incidence
The angle between an incoming ray and the normal.

Make a hypothesis first

Guess: where does the energy go?

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

rectangular glass block
ray box
protractor
plain paper

⚠️ Safety first

Glass blocks chip — check for sharp edges before handling.

Step 1 of 4 · Read

Think about what you just learned: say what "refractive index" and "angle of incidence" mean in your own words before you start.

Step 2 of 4 · Do

Trace rays through a rectangular glass block at five angles of incidence, marking entry and exit. Measure the angles inside and outside and calculate the refractive index from the ratio of their sines.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 2

Light entering glass from air bends:

How sure are you?😐 maybe

Question 2 of 2

Refraction happens because light changes its:

How sure are you?😐 maybe

Mind = blown

⚡ Static electricity is the same physics as lightning, just smaller.

Nice work!

You got 0 of 2 right.

Next: Converging and Diverging Lenses All lessons

🎯

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✨ More to explore

🌍 Where you see this in real life: This is why airplanes can fly and why rockets reach space.

🏆 Stretch challenge (try it this week): This week, find one thing in your house that turns one kind of energy into another.

👨‍👩‍👧 For the dinner table: “Show me something at home that uses this kind of energy.”

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