An air bubble in a glass slab (µ = 1.5) is 6 cm deep when viewed from one face and 4 cm deep when viewed from the opposite face. The thickness of the glass plate is
Answer & explanation
Correct answer: option 3
Let the thickness of slab be t and distance of air bubble from one side is x
When viewed from side (1): 6 = $\frac{x}{1.5}$ ⇒ x = 9 cm
When viewed from side (2): 4 = $\frac{(t-x)}{1.5}$ ⇒ 4 = $\frac{(t-9)}{1.5}$ ⇒ t = 15 cm
Formula used: $D_{\text {apparent }}=\frac{D_{\text {actual }}}{\mu_{\text {rel }}}$