Describe the experimental procedure to determine the refractive index of a glass block using optical pins.

Question

ScanSolve AI Tutor · Accepted Answer

Here's a breakdown of how to perform the experiment described in the question:

a) Steps 1-3: Setup

Use the vernier calipers to measure the width (w) of the glass block.
Take several readings at different points and calculate the average width.
Secure a plane sheet of paper onto a wooden board using thumb tacks.
Place the cuboidal glass block near the center of the paper.
Using a pencil, carefully trace its outline, labeling the vertices A, B, C, D.
- b) Steps 4-6: Incident Ray Preparation
Remove the glass block.
Along the line DC, measure 3.0 cm from point D and mark this point as P.
At point P, use a protractor to draw a line normal (perpendicular) to DC.
Extend this normal line until it meets the line AB at point R.
Draw an incident ray (a straight line) from a point to the left of P, such that it meets the interface DC exactly at point P.
This line represents the path of light entering the block.
- c) Step 7: Tracing the Refracted Ray
Replace the glass block precisely on its outline.
- Insert two optical pins, P₁ and P₂, vertically along the incident ray drawn in Step 6. Ensure P₂ is placed exactly at point P. The pins should be perpendicular to the plane of the paper.
- Looking through the glass block from face AB, observe the images of pins P₁ and P₂. Insert a third optical pin, P₃, along the line AB such that P₁, P₂, and P₃ appear to be in a straight line when viewed through the glass block. This pin marks a point on the emergent ray.
- d) Steps 8-9: Measurements
Carefully remove the glass block and all pins.
Draw a straight line connecting P₂ and P₃. This line represents the refracted ray inside the glass block. Mark the point Q where this refracted ray meets the face AB.
Step 9
- Using a protractor, measure the angle of incidence, θ. This is the angle between the incident ray (from Step 6) and the normal (from Step 5) at point P.
- Using a ruler, measure the length QP. This is the length h of the refracted ray inside the glass block.
- e) Step 10: Data Collection
Replace the glass block on its outline.
To obtain different values of θ, change the position of pin P₁ (and thus the incident ray). Repeat steps 6 through 9 for at least five to six different angles of incidence. Record your measured values of θ and h in a table of values. Your table should include columns for θ, sin θ, h, and 1/h.
- f) Step 11: Graph Plotting
Calculate the values of sin θ and 1/h for all the data points recorded in your table.
Plot a graph with sin θ on the vertical axis and 1/h on the horizontal axis. Draw the best-fit line through your plotted points.

Describe the experimental procedure to determine the refractive index of a glass block using optical pins.

Step-by-step solution

Use the vernier calipers to measure the width (w) of the glass block.

Secure a plane sheet of paper onto a wooden board using thumb tacks.

Place the cuboidal glass block near the center of the paper.

Remove the glass block.

At point P, use a protractor to draw a line normal (perpendicular) to DC.

Draw an incident ray (a straight line) from a point to the left of P, such that it meets the interface DC exactly at point P.

Replace the glass block precisely on its outline.

Carefully remove the glass block and all pins.

Step 9

Replace the glass block on its outline.

Calculate the values of sin θ and 1/h for all the data points recorded in your table.

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