Straight Line Question 246

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

Options:

A) $ (0,3) $

B) $ (0,2) $

C) $ (0,5) $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

  • [c] The point of coincidence on the y-axis is $ Q(0,\lambda ). $ The image of $ P(2,3) $ on the y-axis is $ P_1(-2,3) $ . $ P_1,Q $ and R are collinear. Therefore, slope of $ P_1Q $ = Slope of $ P_1R $ or $ \frac{\lambda -3}{0-(-2)}=\frac{10-3}{5-(-2)} $ or $ \lambda -3=2or\lambda =5. $ Therefore, the point Q is (0, 5)