Question

A ray parallel to x-axis hits a mirror given by equation $x=2y^2$ and becomes parallel to y-axis after reflection as shown in figure. Value of h can be

• A. 0.25
• B. 0.5
• C. 0.35
• D. 1

Answer 1

The correct option is A 0.25


For the reflected ray to be vertical, the angle of incidence should be equal to ${45}^{\circ }$
$\tan \theta =\frac{dy}{dx}=1$

$dx=4ydy\Rightarrow \frac{dy}{dx}=\frac{1}{4y}=1$

$y=\frac{1}{4}=0.25$