Question

The speed of light in vacuum is approximately:

Options

• \[3 \times 10^6 \ \text{m/s}\]

• \[3 \times 10^8 \ \text{m/s}\]

• \[3 \times 10^8 \ \text{km/s}\]

• \[1.5 \times 10^8 \ \text{m/s}\]

Answer 1

Light travels in vacuum at \[c \approx 3 \times 10^8 \ \text{m/s}\]. This constant is used together with the refractive index relation \[n = \frac{c}{v}\] to determine the speed of light inside any material medium.