M

#### missmia

**[SOLVED] Lenses - Thin-Lens Equation and Magnification Equation**

I can't figure out what I am doing wrong, your help would be greatly appreciated :)

__Here is the Homework Problem__

A camera is supplied with two interchangeable lenses, whose focal lengths are 35.0 and 150.0 mm. A woman whose height is 1.80 m stands 9.00 m in front of the camera. What is the height (including sign) of her image on the film, as produced by each of the following.

(a) the 35.0 mm lens

(b) the 150.0 mm lens

**ATTEMPTED SOLUTION:**

[tex]\frac{1}{d_{i}}[/tex] = [tex]\frac{1}{.0035m}[/tex] - [tex]\frac{1}{9.0m}[/tex]

which gives [tex]d_{i}[/tex] = .003501m

then, I used the magnification equation: m = - [tex]\left[\frac{.003501m}{9.0m}\right][/tex] = -3.89 x [tex]10^{-4}[/tex]x

then, I used [tex]h_{i}[/tex] = m[tex]h_{o}[/tex] = -3.89 x [tex]10^{-4}[/tex] x 1.80m = -7.00 x [tex]10^{-4}[/tex]

But, the answer that I got is incorrect! Please Help! Thank you!