Saved Bookmarks
| 1. |
Calculate (a) the refracting angle of a flint glass prism which should be combined with a crown glass prism of refracting angle 6° so that the combination may have no deviation for D line and (b) the angular separation between the C and F lines, given that the refractive indices of the materials are as follows: |
|
Answer» Solution : LET `A_1` and `A_2` be the refracting angles of the FLINT and crown GLASS prisms respectively. `mu_1 ` and `mu_2` be the refractive indices for the D line of flint and crown glasses respectively. (a) If `delta_1 , anddelta_2`, be the angles of deviations due to the flint and crown glass prisms respectively, then for no deviation of D line `DELTA _1+delta _2 =0 , A_1( mu_1-1)+ A_2(mu_2 -1) =0` ` (A_1)/(A_2)=- ((mu_1-1)/(mu_1))` The negative sign indicates that `A_1` and `A_2` are oppositely directed. ` (A_1 )/(6^0 ) = ((1.530 -1)/(1.795-1)) , A_1= 6^0 xx (0.530)/( 0.795)=-4^@ ` (b)Angular dispersion due to the flint glass prism `=A_1(mu_F - mu_C)_2= 6^@( 1.535- 1.527) = 0.048 ` Net angular dispersion = 0.048 -0.060 = -0.012 The negative sign indicates that the resultant dispersion is in the direction of the deviation produced by the flint prism. |
|