Negative Focal Length and Convex Mirrors: Is 1/di Negative?

[luysion]

Hey,
When dealing with convex mirrors I know that the image will always be virtual,upright and diminished. So when I am using descartes's formulae i know that for convex mirrors that the focal length is negative, but does my 1/di become negative? because virtual images have a negative height and distance.

Cheers

 

[Doc Al]

Yes, the image distance is negative for a convex mirror. (This follows directly from the spherical mirror equation.)

 

[astrokreng]

,

Yes, in the case of convex mirrors, the 1/di will also be negative. This is because the distance of the virtual image from the mirror is measured in the opposite direction of the incident light, making it a negative value. This also aligns with the fact that the virtual image has a negative height and distance, as you mentioned. It is important to remember that the negative sign in front of the focal length and 1/di indicates the direction of the image and not its size. I hope this helps clarify any confusion.