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Physics · Practical apparatus

Travelling-microscope slab readings

Practical apparatus

Focus successively on the lower mark, upper surface and apparent lower mark. Differences remove the arbitrary reference reading. Resolution and focus error influence the resulting index ratio.

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Travelling-microscope slab readings

கீழ் குறி, மேல் முகம், தோன்றும் கீழ் குறி ஆகியவற்றில் தனித்தனியாகக் குவித்து வாசிக்கவும். வாசிப்பு வேறுபாடுகளிலிருந்து n கிடைக்கும்.

Key notes, relationships and model limits

Key relationship

n=(Rtop−Rbottom)/(Rtop−Rapparent); apparent depth=true depth/n.

Practical tip

Focus successively on the lower mark, upper surface and apparent lower mark. Differences remove the arbitrary reference reading. Resolution and focus error influence the resulting index ratio.

Common trap

The raw microscope coordinate is not a depth; differences are required.

Model limits

Normal-view apparent depth; homogeneous plane slab. Quantized readings and an explicit focus offset simulate instrument effects without random measurement claims.

What you will learn

Calculate index from three quantized focus readings.

Try the experiment

Try both scenarios, change one control, and predict the result before checking the graph and readouts.

Think of it this way

Change one input while keeping the others fixed, as you would in a controlled experiment.

Worked example

A10 mm slab with n1.5 has apparent depth6.667 mm.

Why this matters

The model connects travelling-microscope slab readings with an observable reading. Check the equation and assumptions before applying it.

Before you start

SI units · algebra · graph reading

Check your understanding

Refractive index from apparent depth is?

Read the explanation

Normal refraction makes a dense slab appear shallower.

Course connection: Virtual apparatus preparation. Check exact board/exam membership in the syllabus sources. Physical practical work remains necessary.