Question

A magnified, inverted image is located a distance of 36.0 cm from a concave mirror with the object distance of 12.0 cm. Determine the focal length.

Answer 1

39.0id the main answer OK I hope this answer is right

Answer 2

Given :

⇒ $D_o$  = -12 cm {Height of Object}

⇒ $D_i$ = -36 cm {Distance of Object}

We used - because It's concave mirror

To Find out :

⇒ f = ?

Formula to be used here :

⇒ $\frac{1}{f} = \frac{1}{D_o} + \frac{1}{D_i}$

Finding out value of f by putting values in above formula :

⇒ $\frac{1}{f} = \frac{1}{-12} + \frac{1}{-36}$

⇒ $\frac{1}{f} = \frac{-1\times3}{12\times3} + \frac{-1}{36}$

⇒ $\frac{1}{f} = \frac{-3}{36} + \frac{-1}{36}$

⇒ $\frac{1}{f} = \frac{-3-1}{36}$

⇒ $\frac{1}{f} = \frac{-4}{36}$

⇒ $f = \frac{-36}{4}$

⇒ $f = \frac{\cancel{-36}}{\cancel{4}}$

∴ Focal Length = -9 cm

Thanks!