Answer:
η = 0.7
Explanation:
The refractive index of the material can be calculated by using the following formula:
[tex]\eta = \frac{c}{v}\\[/tex]
where,
η = refractive index of the material = ?
c = speedof light in vaccuum = 3 x 10⁸ m/s
v = speed of light in this material = 4.3 x 10⁸ m/s
Therefore,
[tex]\eta = \frac{3\ x\ 10^8\ m/s}{4.3\ x\ 10^8\ m/s}[/tex]
η = 0.7