A thin prism \({P}_{1}\) with angle 4° made of glass having refractive index 1.54 , is combine with another thin prism \…

A thin prism \({P}_{1}\) with angle 4° made of glass having refractive index 1.54 , is combine with another thin prism \({P}_{2}\) made of glass having refractive index 1.72 to get dispersion without deviation. The angle of the prism \({P}_{2}\) in degrees is

(Shift - I Memory based)