Refractive index of medium 1 w.r.t 2 = 

Snell’slaw

Relation between refractive index and critical angle = 

For refraction through a spherical surface, from rarer to denser medium = 

Thin lens formula is given by 

Power of a lens

For two lenses in contact, the total power is 

For two lenses in contact, the total magnification is 

For refraction through a prism, the correct relation is 

For refraction through prism, in the condition of minimum deviation

For a simple microscope, if the final image is formed at the least distance of distinct vision, the magnifying power is

For a simple microscope, if the final image is formed at infinity, the magnifying power is

The magnification for a compound microscope, when the final image is formed at the least distance of distinct vision is given by 

The magnification for a compound microscope, when the final image is formed at infinity is given by 

In normal adjustment (when the image is formed at infinity), the angular magnification for an astronomical telescope is given as 

The angular magnification for an astronomical telescope when the final image is formed at least distance of distinct vision is given as 

In normal adjustment (when the image is formed at infinity), the tube length for an astronomical telescope is given as 

In normal adjustment (when the image is formed at infinity), the  distance between objective and eyepiece for an astronomical telescope is given as