A Small Pin Fixed on a Table Top is Viewed from Above from a Distance of 50 Cm. by What Distance Would the Pin Appear to Be Raised If It is Viewed from the Same Point Through a 15 Cm - Physics

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A small pin fixed on a table top is viewed from above from a distance of 50 cm. By what distance would the pin appear to be raised if it is viewed from the same point through a 15 cm thick glass slab held parallel to the table? Refractive index of glass = 1.5. Does the answer depend on the location of the slab?

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Solution

Actual depth of the pin, d = 15 cm

Apparent depth of the pin = d'

Refractive index of glass, μ = 1.5

Ratio of actual depth to the apparent depth is equal to the refractive index of glass, i.e.

`μ = "d"/"d'"`

∴ d' = `"d"/μ`

= `15/1.5`

= 10 cm

The distance at which the pin appears to be raised = d' − d = 15 − 10 = 5 cm

For a small angle of incidence, this distance does not depend upon the location of the slab.

Concept: Refraction
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Chapter 9: Ray Optics and Optical Instruments - Exercise [Page 345]

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NCERT Physics Class 12
Chapter 9 Ray Optics and Optical Instruments
Exercise | Q 9.16 | Page 345
NCERT Physics Class 12
Chapter 9 Ray Optics and Optical Instruments
Exercise | Q 16 | Page 347

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