Q115 / 150 · MHT CET 2024 (11 May Shift 1) · Physics

An ink mark is made on a piece of paper. A glass slab of thickness 't' is placed on it. The ink mark appears to be raised up through a distance ' $x$ ' when viewed at nearly normal incidence. If the refractive index of material of glass slab is ' $\mu$ ' then thickness of glass slab ' $t$ ' is given by

  • A
    $\frac{(\mu-1)}{\mu \mathrm{x}}$.
  • Correct answer
    B
    $\frac{\mu x}{(\mu-1)}$
  • C
    $\frac{(\mu-1) x}{\mu}$
  • D
    $\frac{\mu}{(\mu-1) x}$

Solution

Here, the normal shift is x The formula for the normal shift is $\begin{aligned} x & =t\left(1-\frac{1}{\mu}\right) \\ t & =\frac{x}{\left(1-\frac{1}{\mu}\right)} \\ \therefore \quad t & =\frac{\mu x}{(\mu-1)} \end{aligned}$

Hence, the correct answer is option: 'B'.

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