Question

sign conentions of all mirror and lenses properly plsss

Answer 1

hello friend..!!

the pole is taken as the origin , the X axis denotes the principal axis , the positive of the axis is taken along the incident rays .

sign conventions for mirror's and lenses :

⇒object distance ' u ' is always negative .

⇒ image distance if formed on the opposite side then it is positive , if formed on the same side where the object is placed then it is negative .

⇒ height measured on upward direction is positive , and if measured downward direction then it is negative . 

⇒focal length for convex mirror/lens is always positive , focal length measured for a concave mirror/lens is always negative .

⇒ the R of a concave mirror are always negative , and R for a convex mirror is always positive . 

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hope it is useful..!!

Answer 2

read total lines i am sure you will get clarity ;-)

first for circle mirrors (concave and vex ) :
if the ray is in the direction of incident ray then take positive if opposite to incident ray then take negative...it means from  (mid point of mirror) 

from the first fig we must take image distance as negative as it is opposite to incident ray(blue) and even object as negative because if we move from center(mid point) to object path then it is opposite to incident ray

2nd fig if you see carefully here is image distance is positive because from point of reference(mid point of mirror) it is in the direction of incident ray (it mean if you move your hand from mid point to image forming point it is in the direction of incident ray :-)      okkkkk   again object is negative see clearly have a nice day if you like my teaching then please share your thoughts with me