When a beam of white light passes through a transparent medium, it disperses into a spectrum of colors due to the varying refractive indices of different wavelengths. Consider a beam of light that is incident on a microscope slide with an angle of 20°. It is observed that the wavelength λ R (630 nm), having a refractive index n R (1.576), is refracted at an angle θ R. The wavelength λ B (470 nm), having a refractive index n B, is refracted at an angle θ R - 0.32°. Calculate n B. Hint: When the refractive index varies by δn (δn<<n) due to the wavelength variation, the angle of refraction varies by δθ.