Q38 / 237 · NTA Abhyas (NEET) 2020 · Physics · Ray Optics

If eye is kept at a depth h inside the water of refractive index and viewed outside, then the diameter of circle, through which the outer objects becomes visible, be

  • A
    hμ2+1
  • B
    hμ2-1
  • Correct answer
    C
    2hμ2-1
  • D
    h2μ2-1

Solution

Let r be the radius of the circle through which other objects become visible. The ray of light must be incident at critical angle C.

sin⁡C=1μ=rr2+h2

μ2r2=r2+h2⇒   μ2-1r2=h2

⇒   r=hμ2-1

∴   Diameter=2r=2hμ2-1

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

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