# Uncertainty in length measurement

I am trying to measure the length and the uncertainty in length of a fiber optic cable for measuring the speed of light. So far, I have measured it the standard way: Using a standard meter scale. I understand that it is not the most accurate way to do it. So I have two questions,

1) How can I measure the length of the cable any other way?

2) If I use this method, is it possible to account for the uncertainty in the measurement? For example, taking the distribution of many length measurements to be Gaussian about a particular mean value (which I can choose to be the value I have measured using a meter rule).

• How much precision do you need? Is the optical fiber at constant temperature (is length vs. temperature a concern)? – David White Jul 13 '19 at 15:38
• We can assume it to be at constant temperature since the experiment will operate in a controlled environment where minor fluctuations in temperature can be neglected. As for precision, we need to know the length precise to 0.01 m (1 cm). – Shaz Jul 13 '19 at 16:14