Question

An object placed 37.5 cm in front of a 15.0-cm focal length convex lens produces an image that is 25.0 cm away from the lens. a) calculate the magnification of the image. b) If the image has a height of -3.56 cm, calculate the object's height.

Answer 1

a. -0.67

b. 5.3 cm

Explanation:

Given:

Distance of object = 37.5 cm

Focal length = 15 cm

Distance of image = 25 cm

a.

We can calculate the magnification as follows:

`\begin{gathered} M=-(d_i)/(d_o) \\ \text{ we replacing} \\ M=-(25)/(37.5) \\ M=-0.67 \end{gathered}`

b.

Knowing the magnification we can calculate the height of the object, just like this:

`\begin{gathered} M=(h_i)/(h_o) \\ \text{ We replacing} \\ -0.67=(-3.56)/(h_o) \\ h_o=(-3.56)/(-0.67) \\ h_o=5.3cm \end{gathered}`