Q23 / 107 · NTA Abhyas (JEE Main) 2020 · Physics · Wave Optics

Young's double-slit experiment is performed in a liquid. The 10th bright fringe in case of the liquid lies where 6th bright fringe lies in a vacuum. The refractive index of the liquid approximately is

  • A
    1.8
  • B
    1.54
  • Correct answer
    C
    1.67
  • D
    1.2

Solution

Fringe width in air is given by 

βair=λDd

Fringe width in liquid will be, βliq=λDμd

(as λ liq = λ air μ )

6βair=10βliq

6 λ D d = 1 0 λ D μ d

μ = 1 0 6 = 1.67

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

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