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# A glass slab of refractive index $1.5$ and thickness $3\;cm$ is placed on a black dot on a piece of paper. A person looks at the mark from a height of $8\; cm$ above it. The dot will appear at a distance.

$(a)\;4 \;cm \\ (b)\;5\;cm \\ (c)\;8\;cm \\ (d)\;10\;cm$

apparent depth of the dot $=\large\frac {real\; depth}{\mu}$
$\qquad=\large\frac{3}{1.5}$
$\qquad= 2\;cm$
The person sees the dot at a distance of $8+2 =10cm$
Hence d is the correct answer.