what power of a lens will change the reading distance from 1 m to 0.25 m
Use mirror formula :
For v = -0.25 , u = -1
You will get focal length f = -1/5
Power P = -(1/f)
So, P = + 5D
For v = -0.25 , u = -1
You will get focal length f = -1/5
Power P = -(1/f)
So, P = + 5D