Question

An air bubble in glass slab (µ = 1.5) when viewed from one side, appears to be at 6 cm and from opposite side 4 cm. The thickness of glass slab is ______.

विकल्प

• 10 cm 

• 6.67 cm 

• 15 cm 

• None of these

Answer 1

An air bubble in glass slab (µ = 1.5) when viewed from one side, appears to be at 6 cm and from opposite side 4 cm. The thickness of glass slab is 15 cm.

Explanation:

Let t₁ represent the thickness of the glass slab as seen from one side, and t₂ represent the thickness as seen from the opposite side.

Distance of air bubble (d) = t₁`(1-(1/mu))`

6 =  t₁`(1-(1/1.5)) = "t"_1/3`

⇒ t₁ = 18 cm

4 = t₂`(1-(1/1.5)) = "t"_2/3`

⇒ t₂ = 12 cm

`"t"_"actual" = ("t"_1+"t"_2)/2`

= `(18+12)/2`

t = 15 cm.