The Skinny on Mirrors
+si = −m =
inverted image =
real image
−si = +m =
upright image =
virtual image
Concave mirrors produce
both real and virtual
images, depending on
the focal length and
object’s distance = +f
Convex mirrors only produce
virtual images = −f
Questions 11-14
An object of height 4 cm is placed 30 cm in front of a concave
mirror whose focal length is 10 cm.
- Where’s the image?
- Is it real or virtual?
- Is it upright or inverted?
- What’s the height of the image?
Here’s How to Crack It
- With so = 30 cm and f = 10 cm, the mirror equation gives
The image is located 15 cm in front of the mirror.
- Because si is positive, the image is real.
- Real images are inverted.
