Determine the sign of the image and object?

[an aspiring doctor]

I know that converging always has a positive focal length for both mirrors and lenses and that diverging always has a negative focal length as well for both mirrors and lenses. However how do you determine the sign of the image and object in mirrors and lenses?

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[NextStepTutor_2]

For images, negative is virtual and positive is real. For objects, positive is in front of the mirror or lens and negative is behind the mirror or lens.

Here's a nifty reference for the rest of the sign conventions: http://faculty.spokanefalls.edu/InetShare/AutoWebs/AsaB/Phys103/MirrorsThinLens.pdf

 

[an aspiring doctor]

Thank you

 

[SN2ed]

Thread closed. These types of questions belong in the MCAT Study Q&A forum only.