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Home » A small pin fixed on a tabletop is viewed from above from a distance of 50 cm. Bywhat distance would the pin appear to be raised if it is viewed from the same pointthrough 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?Answer:
A small pin fixed on a tabletop 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?
Answer:
CBSE | Class 12 | NCERT | Physics | Ray Optics and Optical Instruments
A small pin fixed on a tabletop 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?
Answer:

According to the question,
The actual depth of the pin is d = 15 cm
Apparent depth of the pin is = d’
Refractive index of glass is

\mu=1.5


here, the ratio of actual depth to the apparent depth and the refractive index of the glass are equal.
i.e.

\mu=\frac{d}{d'}

Therefore we have –

d’=\frac{d}{\mu}

= \frac{15}{1.5}

= 10cm
The distance at which the pin appears to be raised is given as –

=d’-d=15-10

= 5cm
The distance is independent of the location of the slab when the angle of incidence is small.

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