An experiment was conducted to determine the speed of light through a fiber optic cable. An electrical signal was sent to an LED. The light from the LED was transmitted down the optical fiber and a pulse was detected at the other end. An oscilloscope was used to measure the time delay between the initial electrical pulse and the detected signal. A diagram of the apparatus is shown below.

When the length of the optical fiber is $80 \mathrm{m}$, the signal on the oscilloscope appears like this.

The length of the optical fiber is varied and the delay between the signals is measured. A graph of the results is shown below.

On a copy of the graph, add the result from when the optical fiber was $80 \mathrm{m}$ long.

 

An experiment was conducted to determine the speed of light through a fiber optic cable. An electrical signal was sent to an LED. The light from the LED was transmitted down the optical fiber and a pulse was detected at the other end. An oscilloscope was used to measure the time delay between the initial electrical pulse and the detected signal. A diagram of the apparatus is shown below.

When the length of the optical fiber is $80 \mathrm{m}$, the signal on the oscilloscope appears like this.

The length of the optical fiber is varied and the delay between the signals is measured. A graph of the results is shown below.

On a copy of the graph, add the result from when the optical fiber was $80 \mathrm{m}$ long. Add a line of best fit to the copy of your graph.

An experiment was conducted to determine the speed of light through a fiber optic cable. An electrical signal was sent to an LED. The light from the LED was transmitted down the optical fiber and a pulse was detected at the other end. An oscilloscope was used to measure the time delay between the initial electrical pulse and the detected signal. A diagram of the apparatus is shown below.

When the length of the optical fiber is $80 \mathrm{m}$, the signal on the oscilloscope appears like this.

The length of the optical fiber is varied and the delay between the signals is measured. A graph of the results is shown below.

On a copy of the graph, add the result from when the optical fiber was $80 \mathrm{m}$ long. Add a line of best fit to the copy of your graph. Find the gradient of your line of best fit.

An experiment was conducted to determine the speed of light through a fiber optic cable. An electrical signal was sent to an LED. The light from the LED was transmitted down the optical fiber and a pulse was detected at the other end. An oscilloscope was used to measure the time delay between the initial electrical pulse and the detected signal. A diagram of the apparatus is shown below.

When the length of the optical fiber is $80 \mathrm{m}$, the signal on the oscilloscope appears like this.

The length of the optical fiber is varied and the delay between the signals is measured. A graph of the results is shown below.

On a copy of the graph, add the result from when the optical fiber was $80 \mathrm{m}$ long. Add a line of best fit to the copy of your graph. Find the gradient of your line of best fit. Using your value for the gradient, calculate the speed of the light through the fiber giving your answer in $\mathrm{m} {\mathrm{s}}^{-1}$.

An experiment was conducted to determine the speed of light through a fiber optic cable. An electrical signal was sent to an LED. The light from the LED was transmitted down the optical fiber and a pulse was detected at the other end. An oscilloscope was used to measure the time delay between the initial electrical pulse and the detected signal. A diagram of the apparatus is shown below.

When the length of the optical fiber is $80 \mathrm{m}$, the signal on the oscilloscope appears like this.

The length of the optical fiber is varied and the delay between the signals is measured. A graph of the results is shown below.

On a copy of the graph, add the result from when the optical fiber was $80 \mathrm{m}$ long. Add a line of best fit to the copy of your graph. Find the gradient of your line of best fit. Using your value for the gradient, calculate the speed of the light through the fiber giving your answer in $\mathrm{m} {\mathrm{s}}^{-1}$. Explain why you would expect your answer above to be less than $300,000 \mathrm{km} {\mathrm{s}}^{-1}$.

An experiment was conducted to determine the speed of light through a fiber optic cable. An electrical signal was sent to an LED. The light from the LED was transmitted down the optical fiber and a pulse was detected at the other end. An oscilloscope was used to measure the time delay between the initial electrical pulse and the detected signal. A diagram of the apparatus is shown below.

When the length of the optical fiber is $80 \mathrm{m}$, the signal on the oscilloscope appears like this.

The length of the optical fiber is varied and the delay between the signals is measured. A graph of the results is shown below.

On a copy of the graph, add the result from when the optical fiber was $80 \mathrm{m}$ long. Add a line of best fit to the copy of your graph. Even without the optical fiber, there was a delay between the initial electrical signal being sent and the detection of a signal from the detector. Use your graph to find this time delay.

Imagine that you work for a company that manufactures optical fibers. You need to convince the local government to spend money on replacing their existing telecommunications wire cables with optical fibers. Write a brief note for the local authority outlining how optical fibers work and how they can be used to transmit information. You should use simple scientific terms in a way that is understandable to non-scientists.

Describe the advantages and disadvantages of optical fibers over traditional wire cables for transmitting the information.

Rural communities sometimes have slow internet speeds available to them. Telecommunication companies often say that it is too expensive to provide faster optical fiber links. Outline a counterargument to this.