A lady is standing in front of a plane mirror at a distance of 1 m from it. She walks 60 cm towards the mirror. The distance of her image now from herself (ignoring the thickness of the mirror) is
[amp_mcq option1=”40 cm” option2=”60 cm” option3=”80 cm” option4=”120 cm” correct=”option3″]
This question was previously asked in
UPSC NDA-1 – 2016
Initially, the lady is at a distance of 1 m (100 cm) from the mirror. Her image is formed 100 cm behind the mirror. The distance between the lady and her image is 100 cm (lady to mirror) + 100 cm (mirror to image) = 200 cm.
The lady walks 60 cm towards the mirror. Her new distance from the mirror is 100 cm – 60 cm = 40 cm.
Her new image is formed 40 cm behind the mirror.
The new distance between the lady and her image is her distance from the mirror + her image’s distance from the mirror = 40 cm + 40 cm = 80 cm.
– Image is behind the mirror.
– Distance between object and image is (object distance) + (image distance) = 2 * (object distance).