OPTICS FORMULAE

1. 
   where   f is the focal length,
               u is the distance between the object and the back of the mirror,
   and       v is the distance between the image and the back of the mirror.
   
   
2. 
   where   m is the magnification,
               u is the distance between the object and the back of the mirror,
   and       v is the distance between the image and the back of the mirror.
   
   NOTE:             For a concave mirror and a converging lens .
                           For a convex mirror and a diverging lens .
   
                           For a real image .
                           For a virtual image .
   
   
3. Snell’s Law:
   
   where   i is the angle of incidence, r is the angle of refraction and n is the refractive index.
   
   
4. 
   
   
5. 
   where   c is the critical angle and n is the refractive index.
   
   
6. 
   where  is the speed of light in a vacuum,  is the speed of light in glass and n is the refractive index.
   
   
7. 
   where  is the speed of light in medium 1,  is the speed of light in medium 2
   and  is the refractive index between the two media.
   
   
8. 
   where P is the power of a lens and f is its the focal length.
   (Remember to express f in metres.)
   
   
9. 
   where P is the power of a pair of lenses in contact,  is the power of the first lens and  is the power of the second lens.
   
   
10. 
    where f is the focal length of a pair of lenses in contact, is the focal length of the first lens and  is the focal length of the second lens.