heres the problem:(adsbygoogle = window.adsbygoogle || []).push({});

a dentist wants a small mirror that, when 2.20cm from a tooth, will produce a 4.5x upright image. what kind of mirror must be used and what must its radius of curvature be?

so i did the following calculations with the mirror equations i learned:

m=4.5

equation to get the di https://www.physicsforums.com/attachment.php?attachmentid=7885&stc=1&d=1159712057

4.5*(-2.20) = di di=-9.9

1/do+1/di=1/f

1/(-2.2) + 1/(-9.9) = 1/f

1/(-2.2)=(-0.454545455)

1/(-9.9)=(-0.101010101)

(-0.454545455)+(-0.101010101)=(-0.555555556)

1/(-0.555555556)=f

1/(-0.555555556)=(-1.8)

f=(-1.8)

f2 = r

-1.8 * 2 = -3.6

so the radius is -3.6 and i guess it is concave as only concave mirrors 1.0+ magnify? that's wrong as my book says the correct answer is 5.66cm, concave. what am i doing wrong

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# Trouble with mirror equations, need help.

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