A ray of light is incident normally on one of the faces of a prism of apex angle 30° and refractive index √2 . The angle of deviation of the ray is

Question

A ray of light is incident normally on one of the faces of a prism of apex angle 30° and refractive index √2 . The angle of deviation of the ray is (A) 30 °  (B) 45 °  (C) 15 °  (D) none of these

Tardigrade Admin · Accepted Answer

Using Snell&rsquo;s law for the refraction at AC , we get μ sini=(.1.) sinr √2sin30° =sinr sinr=(1/√2) ⇒ r=45° ∴ Angle of deviation =45° -30° =15° <img class="img-fluid question-image" alt="Solution" src="https://cdn.tardigrade.in/q/nta/p-jl69m1ykki6y.png" />

Q. A ray of light is incident normally on one of the faces of a prism of apex angle $3 0^{\circ}$ and refractive index $2$ . The angle of deviation of the ray is

$3 0^{\circ}$

$4 5^{\circ}$

$1 5^{\circ}$

none of these

Using Snell’s law for the refraction at $A C$ , we get
$μ s ini = (1) s in r$
$2 s in 3 0^{\circ} = s in r$
$s in r = \frac{1}{2}$
$\Rightarrow r = 4 5^{\circ}$
$∴$ Angle of deviation $= 4 5^{\circ} - 3 0^{\circ} = 1 5^{\circ}$

Q. A ray of light is incident normally on one of the faces of a prism of apex angle 30∘ and refractive index 2​ . The angle of deviation of the ray is

30∘

45∘

15∘