The correct relation between magnification m, object distance u and focal length f of a spherical mirror is
Answers
The correct relation between magnification m, object distance u, and focal length f of a spherical mirror is m = f/(f - u) .
We know that the magnification of a spherical mirror is given by the formula:
m = - v/u
where v is the image distance
and u is the object distance
This equation could be rewritten as v = -mu. Let this be equation 1
Now, we also know the mirror formula, to obtain the reciprocal of focal length f, which is 1/f = 1/v + 1/u. Let this be equation 2
Now, substitute equation 1 in equation 2. We get:
1/f = 1/(-mu) + 1/u
⇒ 1/f = -1/mu + m/mu
⇒ 1/f = (m-1)/mu
⇒ f = mu/(m-1)
⇒ f(m-1) = mu
⇒ fm - f = mu
⇒ fm - mu = f
⇒ m(f - u) = f
⇒ m = f/(f - u)
This is the correct relation between magnification m, object distance u, and focal length f of a spherical mirror
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