Please help me with Physics- Topic is Optics?

Question

A beam of light is traveling in air and strikes a material. The angles of incidence and refraction are 63.0 degrees and 47.0 degrees, respectively.

(a) Please obtain the speed of light in the material.

Answer 1

N1 = 1

N2 = sin(Θ1)*N1/sin(Θ2) = 1.2183

c = 3E8/N2 = 2.46245E8 m/s

Answer 2

v = speed of light in the medium

i = angle of incidence

R = angle of refraction

c = speed of light in a vacuum

i = 63.0 degrees

R = 47.0 degrees

c = 1,079,252,848.8 km/h = 299,792.458 km/s

c ~= 300,000 km/s (approximately)

c = 670,616,629.4 miles per hour = 983,571,056.4 feet per second

Snell's Law: (sin i) / (sin R) = n

n = constant ratio of the speeds of light in two media.

n  = c/v

nv = c

v  = c/n

v  = c/((sin i) / (sin R))

v  = (c sin R) / (sin i)

v  = 299,792.485 km/s x sin 47 degrees / sin 63 degrees

v  = 246,074 km/s