The speed of light is around ________ in vacuum.

Q.

What is the speed of light in vacuum? Mention a condition in which the speed of light changes.

Q. The ratio of the speed of light in a vacuum to the speed of light in a particular material is called what?

Q. When light travels in a transparent medium, the speed of light decreases by a factor of $1.5$ as compared to the speed in vacuum. The refractive index of the material is-

Q. The speed of light in medium $b$ is $\frac{c}{3}$, where $c=$ speed of light in vacuum and light refracts from medium $a$ to medium $b$ making angles ${45}^{\circ }$ and ${60}^{\circ }$ respectively with normal. The speed of light in medium $a$ is

Q. A certain color of light towards the purple end of the visible spectrum has a wavelength of $420nm$ in a vacuum.
What is the frequency of this light?
The speed of light in a vacuum is $3.00\times {10}^{8}m/s$