What does “Lens/mirror formula & magnification” actually mean in Ray Optics & Optical Instruments, and why does it matter for JEE?
1/v − 1/u = 1/f links object, image and focal length; magnification m = v/u tells size and orientation.
In simple words: 1/v − 1/u = 1/f links object, image and focal length; magnification m = v/u tells size and orientation. Getting Lens/mirror formula & magnification clear matters because JEE questions on Ray Optics & Optical Instruments usually test this idea directly, not just a formula you memorised.
Key point
Lens/mirror formula & magnification
Common mistake
ignoring the sign convention, which flips the meaning of the answer.
Memory tip
stick to one sign convention (distances measured from the pole) throughout.
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