Question

What is the speed of light in vacuum?

• A. $3\times {10}^{10}\mathrm{m}/\mathrm{s}$
• B. $3\times {10}^8\mathrm{m}/\mathrm{s}$
• C. $2\times {10}^{10}\mathrm{m}/\mathrm{s}$
• D. $1.5\times {10}^8\mathrm{m}/\mathrm{s}$

Answer 1

The correct option is B

$3\times {10}^8\mathrm{m}/\mathrm{s}$

1. Speed is defined as the distance travelled per unit of time.
2. Vacuum is a space having no matter and very low pressure.
3. So, light can travel without any obstruction caused by the matter and has a maximum speed in the vacuum.
4. The speed of light in the vacuum is $3\times {10}^8\mathrm{m}/\mathrm{s}$.

Therefore, option B is correct.