Identify the correct statements.
(A) A concave mirror is preferred over a plane mirror for the purpose of shaving.
(B) The absolute refractive index of a medium can be less than unity.
(C) Snell's law gives the relative refractive index of a medium.
(D) When a convex lens is placed inside a transparent medium of refractive index greater than that of its own material, it behaves as a diverging lens.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (C) and (D) only
(A) True: A concave mirror is preferred for shaving because it can form an enlarged virtual image when the face is within its focal length.
(B) False: Absolute refractive index $n = \frac{c}{v} \geq 1$, since $v \leq c$. It cannot be less than unity.
(C) True: Snell’s law $\frac{\sin i}{\sin r} = \frac{n_{2}}{n_{1}}$ gives the relative refractive index of medium 2 with respect to medium 1.
(D) True: If the surrounding medium has refractive index greater than the lens material, the convex lens behaves like a diverging lens.
Correct statements: (A), (C), (D)