In an experiment to measure the focal length of a concave mirror. If was found that for an object distance of 0.30 m, the image distance come out to be 0.60 m. Let us determine the focal length.

Explanation

By mirror formula, `{:(,,u=-0.30m),((1)/(v)+(1)/(u)=(1)/(f), rArr,),(,,v=-0.60m):}`
`rArr (1)/(f)=(-1)/(0.30)-(1)/(0.60)rArr (1)/(f)=(-3.0)/(0.60)rArrf =0.20m`
As `(1)/(f)=(1)/(v)+(1)/(u)rArr(-df)/(f^(2))=(-dv)/(v^(2))-(du)/(u^(2))rArrdf=(0.20)^(2)[(0.01)/((0.60)^(2))+(0.01)/((0.30)^(2))]rArrdf=0.0055~~ 0.01 m`
`:.` Focal length `f=(0.20 pm0.01)m`.