"A concave mirror of focal length 1m is used to magnify an object by a factor of 4. Where is the object in relation to the pole of the mirror?"(adsbygoogle = window.adsbygoogle || []).push({});

Heres what i did:

[tex]

\begin{array}{c}

M = \frac{v}{u} \\

\therefore 4 = \frac{v}{u} \\

\therefore v = 4u \\

\end{array}

[/tex]

[tex]

\begin{array}{c}

\frac{1}{f} = \frac{1}{u} + \frac{1}{v} \\

\therefore 1 = \frac{1}{u} + \frac{1}{{4u}} = \frac{5}{{4u}} \\

\therefore u = 1.25m \\

\end{array}

[/tex]

Where am i going wrong? According to my textbook, the answer is 0.75m.

Thanks in advance,

Dan.

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# Homework Help: Concave mirrors - where is the object

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