A prism of angle $\mathrm{A}=1^{\circ}$ has a refractive index $\mu=1.5$. A good estimate for the minimum angle of deviation (in degrees) is close to N/10. Value of N is ____.

JEE Main · 2020 · 05 Sep 2020 · Shift 2 · Geometrical Optics

A prism of angle

A = 1^{\circ}

has a refractive index

μ = 1.5

. A good estimate for the minimum angle of deviation (in degrees) is close to N/10. Value of N is ____.

Answer: 5

Solution

For a thin prism the deviation is

δ = (μ - 1) A

, independent of the angle of incidence for small angles. With

μ = 1.5

and

A = 1^{\circ}

δ = (1.5 - 1) \times 1^{\circ} = 0. 5^{\circ}

. Writing this as

\frac{N}{10}

degrees,

0.5 = \frac{N}{10}

gives

N = 5

JEE Main · 2020 · 05 Sep 2020 · Shift 2 · Integer answer

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