Question: Q. 7. For the same value of angle of incidence, the angles of refraction in three media $A, B$ and $C$ are $15^{\circ}, 25^{\circ}$ and $35^{\circ}$ respectively. In which medium would the velocity of light be minimum ?
U [OD 2012]
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Solution:
Ans. Velocity of light would be minimum in medium ’ $A$ ‘.
[CBSE Marking Scheme 2012] 1
Detailed Answer :
Since the refractive index of the material
$$ n=\frac{c}{v}=\frac{\sin i}{\sin r} $$
where, $c$ is the velocity of light in vacuum and $v$ is velocity of light in that medium.
Refractive index shows the material’s bending power of light. Hence for same value of angle of incidence, the material in which angle of refraction is minimum that would have greatest refractive index. So, A has maximum refractive index and hence velocity of light is minimum in it.
