Least count of Vernier of travelling microscope =_____________mm
Record two such data – with and without water
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S.No. |
Order of Dark or bright ring |
Microscope reading |
Diameter |
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Left side |
Right side |
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m |
MSR |
VC |
L = MSR+ VC*LC (cm) |
MSR |
VC |
R = MSR+ VC*LC (cm) |
D R-L (cm) |
D2 (cm2) |
Dn+m2-Dn2 (cm2) |
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Plot the following Graphs
First use the data recorded without water and plot D2 vs. m. Perform a best-fit calculation and plot. From the slope of the graph, calculate the radius of curvature R of the Plano-convex lens as : $$R=(slope)\times\frac{1}{4\lambda }=\_\_\_cm$$ (when thin air film is used) Then use the data recorded for with water and plot D2 vs. m. Perform a best-fit calculation and plot. From the slope of the graph, calculate the refractive index (µ) of thin film that is enclosed between the lower surface of the lens and upper surface of the glass plate as : $$ \mu=\frac{4\lambda R}{(slope)}=\_\_\_cm $$