Key relationship
s=t sin(i−r)/cos r; sin i=n sin r; observed s rounded to0.01 cm plus offset.
Physics · Practical apparatus
Glass-slab pin and shift reading
The two outside pin lines should be parallel. Measure their shortest separation, not their horizontal coordinate difference. Compare this shift with Snell’s law and correct an introduced ruler offset.
Open the interactive experiment →Glass-slab pin and shift reading
வெளிப்புற ஊசி வரிகள் இணையாக இருக்கும். அவற்றின் குறைந்தபட்ச செங்குத்துப் பிரிவையே பக்க நகர்வாக அளக்கவும்.
Key notes, relationships and model limits
Practical tip
The two outside pin lines should be parallel. Measure their shortest separation, not their horizontal coordinate difference. Compare this shift with Snell’s law and correct an introduced ruler offset.
Common trap
The emerging angle is restored; the emerging line is displaced.
Model limits
Parallel glass slab and ideal pin-alignment ray; ruler quantization and explicit zero offset. No pin-placement random errors are inferred.
What you will learn
Trace pin rays and distinguish true shift from a ruler reading.
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
At normal incidence the true shift is0 even when a ruler offset reports0.05 cm.
Why this matters
The model connects glass-slab pin and shift reading with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
Lateral shift is measured as?
- Any horizontal difference
- Perpendicular separation of parallel ray lines
- Slab thickness always
Read the explanation
The shift formula describes shortest line separation.
Course connection: Virtual apparatus preparation. Check exact board/exam membership in the syllabus sources. Physical practical work remains necessary.