Optics Question 518
Question: A plane mirror is approaching you at a speed of $ 10cm/sec $ You can see your image in it. At what speed will your image approach you
[CPMT 1974]
Options:
A) $ 10cm/sec $
B) $ 5cm/sec $
C) $ 20cm/sec $
D) $ 15cm/sec $
Show Answer
Answer:
Correct Answer: C
Solution:
Suppose at any instant, plane mirror lies at a distance x from object.
Image will be formed behind the mirror at the same distance x.
When the mirror shifts towards the object by distance $y$ the image shifts $ =x+y-(x-y)=2y $ .
So speed of image = 2 x speed of mirror
