Question

In an equilateral glass prism, for two angles of incidence, differing by ${10}^o$, the angle of deviation is found to be ${40}^o$, find these angles of incidence.

Answer 1

We know the formula,
$\delta =i_1+i_2-A$
$i_2=i_1+10$
And, $A=60$ (for equilateral prism)
$\delta ={40}^o$ (given)
$\therefore 40=i_1+i_1+10-60$
$i_1={45}^o$ and $i_2=i_1+10={45}^o+10={55}^o$