some formulas in optics

 

1)

 = 2pi (x) / lamda

 

 

 = phase diff.  ................del. x is path diff.

 

 

 

 

2)normal shift

 

S = t (1 -   1/).....................( is not whole divided)

 

S_water = t/4

 

S_glass = t/3

 

 

 

3)wen a lens is cut into 2 = parts  perpendicular to its principal axis , focal length gets doubled and power gets halved

 

 

4)wen a lens is cut into 2 = parts parallel to its P. Axis , no change in focal length or power takes place

 

 

5)Goggles donot hav any power coz R1 = R2 = R for them

 

so p = ( - 1) (1/R1 - 1/R2)

 

 

 

 

6)wen a lens is submerged in a denser medium its focal length inc and power dec.

 

 

7)wen a lens is submerged in water its focal length inc by 4 times and power dec. by 4 times

 

 

 

8)wen a lens is submerged in a medium of greater R.I then its nature reverses

 

 

 

9)Min. length of a plane mirror reqired to see full image of the object of ht. 'h' is h/2

 

 

10)*  formula to calculate no. of images frmed b/w 2 mirrors is given by

 

n = 360/theta - 1

 

eg. if theta is 60.

then n = 5