Until today I learned in geometric optics that(adsbygoogle = window.adsbygoogle || []).push({});

- Object distance +ve for real object else -ve
- Image distance +ve for real image else -ve
- Radius of curvature +ve for if light comes to the surcace from the side lying center of curvature else -ve

On the basis of this the lens formula would be

1/u + 1/v = 1/f [u=obj distance v= image distance f= focal length]

But recently, the new text book i follow writes that. "All distances towards the left of the lens are taken -ve and all other to the right are positive"

For a convex lens if the object is beyond 2f at a finite distance the new sign convention would give 1/v - 1/u = 1/f ;

I know it will not cause problem if i stick to one convention only but i wish to follow universal convention. So i would like to know if there is anything like "Universal sign convention"for geometric optics

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# Sign convention in geometric optics.

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