What is the image distance for a concave mirror using the mirror equation?

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Homework Statement

B) Using the mirror equation, find the image distance.

Homework Equations

1/do + 1/di = 1/f

The Attempt at a Solution

[/B]
B)
do = 2cm f = 4cm
1/do + 1/di = 1/f
1/di = 1/f - 1/do
1/di = do/f(do) - f/f(do)
1/di = (do-f)/(f*do)
di = (f*do)/(do-f) = (4cm * 2cm)/(2cm - 4cm) = (8cm^2)/(-2cm) = -4cm
di = -4cm

 

[toothpaste666]

is it ok that my image distance came out negative? if i am correct this is fine if the image is behind the mirror

 

[ehild]

It is correct, the distance of a virtual image is negative in the frame of sign convention you applied.

 

[toothpaste666]

thank you!