Explain me sign convection for mirrors,lens,and spherical surfaces in simple way...

Hi ! Sunkari,

     for all lenses , mirror and spherical mirror the distance on the principal axis are measure from the optical centre.

      All distance measure above the principal axis are (+ve) and measure below the principal axis are (-ve).

      type                     u               v                     f                         h_i                                           h_o

                                           real         virtual     real      virtual      real        virtual

Concave lens               –        No            –           No         –          No           +                     +

 

concave  ||                   –         –              +            –          –         +              –                     +

      

@ sunkari 
1- all distance from principal axis are measured from optical enter . 
2-the distance measure in the direction of incident ray are +ve and opp. to that are -ve  
3- all distance above the principal axis are +ve , thus height of object of an erect image are +ve 
4- below the principal axis its -ve 
for convex 
image – +ve ( real ) , -ve ( virtual ) 
object – +ve (real ) , virtual – no virtual focus 
height – 

 real (-ve ) virtual ( +ve ) 
height of object – always +ve . 
HOPE IT CLEARS YOUR DOUBT 
ALL THE BEST ..