00:01
Hello students in the question we are given near point of a person's eye.
00:06
So we have near point of a person's eye equal to 74 .0 cm and we are given that object is placed at distance equal to 24 .0 cm.
00:41
So a person can see clearly if image is formed at person's near point.
01:15
So here we can write object distance u it is equal to minus 24 .0 cm.
01:30
We have a minus sign by sign convention because object is placed in front of lens and here we have image distance v equal to near point of person's eye minus 74 .0 cm.
01:53
This distance is also in front of lens.
01:56
We have a negative sign and we have formula 1 upon focal length is equal to 1 upon image distance minus 1 upon object distance.
02:06
We can write this is equal to lcm v into u and in numerator we have u minus v from here we get focal length f is equal to v u divided by u minus v.
02:23
Let us substitute the values here we get minus 74 .0 into minus 24 .0 divided by minus 24 .0 minus of minus 74 .0 we get f is equal to 74 .0 into 24 .0 divided by 24 .0 minus plus 74 .0 this comes out to be equal to plus 35 .52 cm.
03:03
So here we have focal length focal length of lens or corrective lens required f is equal to plus 35 .5 cm...