Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

If light is switched ON, only for a second, and the distance between the observer and the light source is 10 million kilometers, can I still see the light spark?

For example, let's assume that the source is the Sun and the observer is a human eye.

share|improve this question
add comment

2 Answers

Yes it can be seen, given that you do not get much noise and that your sensor is sensitive enough for it to be able to detect the signal. As you have not specified anything about the light not much can be concluded, more than that it depends on the sensor, the transmitter and the noise from everything else.

share|improve this answer
add comment

To provide some further Information: The Intensity of the (ballistic) Light is described by Beer-Lambert law, so it is exponentially decaying.

$I=I_{0}e^{-\mu_{e} x}$ where $\mu_{e}$ is known as extinction coefficient. It is the sum of the absorbtion and scattering coefficent. $\mu_{e}=\mu_{s}+\mu_{a} = \frac{1}{l_{s}} + \frac{1}{l_{a}}$

So you have to know the Intensity of your lightsource, the coefficient (which depends on frequency, for the atmosphere some wavelengths are strongly scattering and for others the atmosphere is nearly transparent) an the sensibility of your detector and the Intensity of the background should be lower than the intensity of your source.

Now you have all the tools you need to find your awnser.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.