A bubble in a glass slab (refractive index1.5) when viewed from one side appears at $5 \mathrm{~cm}$ and at…
A bubble in a glass slab (refractive index1.5) when viewed from one side appears at $5 \mathrm{~cm}$ and at $2 \mathrm{~cm}$ from other side then thickness of the slab is
2.5 cm
3 cm
10.5 cm
3.75 cm
Solution
Let the thickness of the glass slab is $t$ and distance of the bubble from one side is $x$.
$\begin{aligned}
& \therefore \frac{x}{\mu}=5 \mathrm{~cm} \quad---(1) \\
& \therefore \frac{t-x}{\mu}=2 \mathrm{~cm} \quad--(2)
\end{aligned}$
By solving equation (1) and (2), we get,
$t=7 \mu \mathrm{cm}=10.5 \mathrm{~cm}$