- #1
x64bob
- 10
- 0
heres the problem:
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
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