A Material Has an Index of Refraction of 1

Multiple Choice

A material has an index of refraction of 1.92 for light from a 560 nm source.What is the speed of light for this wavelength within the material? (c = 3.00 × 10⁸ m/s)

A) 2.19 × 10⁸ m/s
B) 4.68 × 10⁸ m/s
C) 1.56 × 10⁸ m/s
D) 1.92 × 10⁸ m/s