# What is the speed of light?

• Rabinow23

#### Rabinow23

Problem Statement: I know that speed of light is 3000km per second
Relevant Equations: Is it true?

Can someone correct me if I 'm wrong,just interested thank-you

Can someone correct me if I 'm wrong,just interested thank-you

Well, it's 299 792 458##\text{ms}^{-1}##, or, equivalently 299 792,458##\text{kms}^{-1}##.

Rabinow23 said:
Problem Statement: I know that speed of light is 3000km per second
Relevant Equations: Is it true?

Can someone correct me if I 'm wrong,just interested thank-you
You dropped a couple of zeroes. And this is the speed in a vacuum; it is slower in other media.

You are off by a factor of 100.
It is 299,792 Km/s

## 1. What is the exact speed of light?

The exact speed of light in a vacuum is 299,792,458 meters per second, or approximately 186,282 miles per second.

## 2. Why is the speed of light considered the cosmic speed limit?

The speed of light is considered the cosmic speed limit because it is the fastest speed at which energy, information, or matter can travel in the universe. This is due to the laws of physics, specifically Einstein's theory of relativity.

## 3. How was the speed of light first measured?

The first measurement of the speed of light was done by Danish astronomer Ole Rømer in 1676. He used observations of the moons of Jupiter to calculate the time it took for light to travel from Jupiter to Earth.

## 4. Does the speed of light ever change?

In a vacuum, the speed of light remains constant. However, in other mediums such as water or air, the speed of light can be slightly slower due to the interaction with particles in the medium.

## 5. Can anything travel faster than the speed of light?

According to our current understanding of physics, nothing can travel faster than the speed of light. This is known as the cosmic speed limit and is a fundamental principle of the universe.