When the angle of incidence is 60? on the surface of a glass slab, it is found that the reflected ray is completely polarised. The velocity of light in glass is

Question

When the angle of incidence is 60? on the surface of a glass slab, it is found that the reflected ray is completely polarised. The velocity of light in glass is (A)  √2× 108ms-1  (B)  √3× 108ms-1  (C)  2× 108ms-1  (D)  3× 108ms-1

Tardigrade Admin · Accepted Answer

Refractive index of glass, μ g= tan θ p where θ p= polarising angle ⇒ μ g= tan 60o=√3 Now, μ g=(c/vg) ∴ (c/vg)=√3 ⇒ vg=(3× 108/√3) =√3× 108m/s

Q. When the angle of incidence is 60? on the surface of a glass slab, it is found that the reflected ray is completely polarised. The velocity of light in glass is

$2 \times 10^{8} m s^{- 1}$

$3 \times 10^{8} m s^{- 1}$

$2 \times 10^{8} m s^{- 1}$

$3 \times 10^{8} m s^{- 1}$

Refractive index of glass, $μ_{g} = tan θ_{p}$ where $θ_{p} =$ polarising angle $\Rightarrow$ $μ_{g} = tan 60^{o} = 3$ Now, $μ_{g} = \frac{c}{v _{g}}$ $∴$ $\frac{c}{v _{g}} = 3$ $\Rightarrow$ $v_{g} = \frac{3 \times 10 ^{8}}{3}$ $= 3 \times 10^{8} m / s$

Q. When the angle of incidence is 60? on the surface of a glass slab, it is found that the reflected ray is completely polarised. The velocity of light in glass is

2​×108ms−1

3​×108ms−1

2×108ms−1

3×108ms−1

Refractive index of glass, μg​=tanθp​ where θp​= polarising angle ⇒ μg​=tan60o=3​ Now, μg​=vg​c​ ∴ vg​c​=3​ ⇒ vg​=3​3×108​ =3​×108m/s

$2 \times 10^{8} m s^{- 1}$

$3 \times 10^{8} m s^{- 1}$

$2 \times 10^{8} m s^{- 1}$

$3 \times 10^{8} m s^{- 1}$

Refractive index of glass, $μ_{g} = tan θ_{p}$ where $θ_{p} =$ polarising angle $\Rightarrow$ $μ_{g} = tan 60^{o} = 3$ Now, $μ_{g} = \frac{c}{v _{g}}$ $∴$ $\frac{c}{v _{g}} = 3$ $\Rightarrow$ $v_{g} = \frac{3 \times 10 ^{8}}{3}$ $= 3 \times 10^{8} m / s$