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General Physics

in mirror formula prove

m=f/f-u.

Profile image of saurabh Sancheti
14 Years agoGrade
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3 Answers

Profile image of Shyama P
14 Years ago

1/f= 1/u+1/v

multiplying with u =>

u/f= 1+u/v

m=-v/u Sub in eqn

u/f-1=-1/m

Solve & u get the ans:

Profile image of Sanandanan M
14 Years ago

(1/v) + (1/u) = (1/f)

(1/v) = (1/f) - (1/u) = ((u-f)/f)

multiply throughout by -u and take reciprocal

-(v/u) = (f/(f-u))

that is magnification.

Profile image of Prashant Sinha
4 Years ago
Mirror Formula- 1/v+1/u=1/f
1/v=(1/f)-(1/u)
1/v=(u-f)/fu
v=fu/(u-f) ---------- (1)
Magnification (m) = -(v)/u
m=-(fu/(u-f))/u           (From (1))
u-f can be written as -(f-u)
so it will become
m=(fu/f-u)/u
m=f/(f-u)        (By cancelling u)
Hence proved.