The distance between the object and the real image formed by a convex lens is d. IF the linear magnificationis m, find the focal length of the lens in terms of d and m.

The distance between the object and the real image formed by a convex

1.	The distance between the object and the real image formed by a convex lens is d. IF the linear magnificationis m, find the focal length of the lens in terms of d and m.
Answer» <html><body><p></p>Solution :The convex lens formula for a real image is <br/> `1/v+1/u=1/f` <br/> Where no sign conventions are to be used, Multiplying by u we get <br/> `u/v+1=u/f or 1/m=u/f-1=(u-f)/f`<br/> or `m(u-f)=f or u=((l+m)f)/m`……..(<a href="https://interviewquestions.tuteehub.com/tag/ii-1036832" style="font-weight:bold;" target="_blank" title="Click to know more about II">II</a>) <br/> Multiplying (i) by v we get <br/> `1+v/u=v/f or 1+m=v/f or v=f(1+m)`......(iii) <br/> Now u+v=d Using (ii) and (iii) wehave <br/> `d=((1+m)f)/m+f(1+m)` which gives `f=(<a href="https://interviewquestions.tuteehub.com/tag/md-557525" style="font-weight:bold;" target="_blank" title="Click to know more about MD">MD</a>)/(1+m)^<a href="https://interviewquestions.tuteehub.com/tag/2-283658" style="font-weight:bold;" target="_blank" title="Click to know more about 2">2</a>`</body></html>