Question

A light ray emerging from the point source placed at $P(2,3)$ is reflected at a point $Q$ on the y-axis and then passes through the point $R(5,10)$. Coordinates of $Q$ are

• A. $(0,3)$
• B. $(0,2)$
• C. $(0,5)$
• D. none of these

Answer 1

The correct option is C $(0,5)$

If $P_1$ be the reflection of $P$ in y-axis then $P_1\equiv (-2,3)$

Equation of line $P_{1}R$ is $(y-3)=\frac{10-3}{5+2}(x+2)$

$\Rightarrow y=x+5.$

It meets y-axis at $(0,5)\Rightarrow Q\equiv (0,5)$