Angular Spread Of Blue and Red Light Through Plastic

[fs93]

Homework Statement

The index of refraction for blue light in plastic is 1.46 and for red light is 1.39. Determine the angular spread of the spectrum leaving the plastic block [presumably to air] for a beam of white light incident at angle of 45° to the plastic block.

Homework Equations

n1/n2=sinI/sinR

The Attempt at a Solution

They are asking for white light, but I am only given blue and red?
Using Snell's law to find:

Blue - 1.46/1=sin45/sinX
sinX=0.48
X= 28.97

Red - 1.39/1=sin45/sinY
sinY=0.52
Y=31.33

Is that right? Would blue would leave at 28.97° and red at 31.33°. What about white light?

Thanks.

 

[kuruman]

What wavelength is white light?