What are the co-ordinates of the image of S formed by a plane mirror as shown in figure

Correct answer is (b) (−4 cm, 0).

Step 1: Recall the rule of image formation in a plane mirror

For a mirror along the y-axis, the x-coordinate changes sign, but the y-coordinate remains the same.

That means if a point is (x, y), its image will be (-x, y).

Step 2: Apply rule to point S

Point S has coordinates (4 cm, 0).

After reflection in the y-axis, the image becomes (-4 cm, 0).

The image of point S(4, 0) in the plane mirror is at (−4 cm, 0) because reflection in the y-axis reverses the x-coordinate while keeping the y-coordinate unchanged.