A parallel beam of light falls on a concave mirror given by equation $y^{2} = 12 x$ Angle between the principal axis of the mirror and the beam equals $3 0^{\circ}$ After reflection, beam gets focused at $(a, b)$ . What is value of $(ab)$ (Round off to the nearest integer)?

Question

TestHub · Accepted Answer

Comparing y 2 = 4 a x & y 2 = 12 x , a = 3 ⇒ f = 3 a = 3 , 3 ​ 1 ​ = 3 ∣ b ∣ ​ , ∣ b ∣ = 3 ​ , ab = 3 × 1.732 = 5.196

Physics - Geometrical Optics Question with Solution | TestHub

Doubts & Discussion

JEE Main 2027 (Class 12)