Dispersion: why violet bends more than red

For a glass, the refractive index depends on the wavelength: $n = 1.5046 + \dfrac{0.0042}{\lambda^2}$, with $\lambda$ in micrometres. You will make the program find $n$ for seven colours, follow each through a $60^\circ$ prism at $50^\circ$, and measure how wide the spectrum is. Then it draws the deviation against the wavelength.

Your tasks.

1. Inside the loop, work out n for the wavelength lam (given in nanometres).
2. Find spread, the deviation of the last colour (violet) minus that of the first (red).
3. Find most, the name of the colour that is bent the most.