# Finding maximum distance of a lit power source

• 02drai
Once you have that, you can set that equal to the 1% of the 60W and solve for the radius.In summary, the minimum energy of visible light that can be detected by the eye is 10e-17W. Only 1% of the power input to a 60W light bulb is emitted between wavelengths of 500 to 600 nm. To estimate the maximum distance at which the lit bulb can be seen, we need to consider the maximum diameter of the pupil (8mm) and the maximum sensitivity of the eye (8% of light incident). By setting the power output per square meter equal to 1% of 60W and solving for the radius, we get a maximum distance of
02drai
The minimum energy of the visible lights of wavelength 500to 600 nm that can just be detected by the eye is 10e-17Watts. Only 1% of power input to a 60W light bulb is emitted between these wavelengths. Estimate the maximum distance that it might be possible to see the lit bulb. The pupil of the eye will be at its maximum diameter say 8mm. At its maximum sensitivity the eye only detect 8% of the light incident on it.

Minimum power the eye can detect= 10e-17w
1% of 60w=0.6w

Therefore, the maximum distance to see the lit bulb,

Power output ÷ surface area of a sphere = power per meter square
0.6÷(4πr^2)=10e-17
0.6÷10e-17=(4πr^2)
(6X10^16)/4π=r^2
so r=sqrt(6X10^16)/4π)
r= 217080km however in answer is 140km.

You're problem is units! There's a reason that you've been given more information that you're actually using. On the left you have power per square meter. But the piece of information you used on the right has units of power.

Break the problem into a couple different stages: figure out how much of the pupil area, which I think should be safe to assume as a circle, relates to that minimum power, and then figure out how much of that quantity relates to the power radiated/m^2.

## 1. What is the process for finding the maximum distance of a lit power source?

The process for finding the maximum distance of a lit power source involves several steps. First, measure the intensity of the light emitted by the power source at a known distance. Then, move the measuring device further away and record the intensity again. Repeat this process until the intensity is too low to be measured accurately. Finally, use mathematical equations to calculate the maximum distance based on the recorded data.

## 2. What equipment is needed to find the maximum distance of a lit power source?

To find the maximum distance of a lit power source, you will need a measuring device such as a light meter, a ruler or measuring tape, and a calculator or computer for performing calculations. It may also be helpful to have a notepad or spreadsheet to record and organize your data.

## 3. How accurate are the results when finding the maximum distance of a lit power source?

The accuracy of the results when finding the maximum distance of a lit power source depends on the precision of the measuring device and the consistency of the recording process. It is important to take multiple measurements at each distance and to use precise equipment for the most accurate results.

## 4. Can this method be used for all types of power sources?

This method can be used for most types of power sources that emit light, such as light bulbs, LEDs, and lasers. However, the accuracy of the results may vary depending on the type and intensity of the light emitted by the power source.

## 5. Are there any other factors that can affect the maximum distance of a lit power source?

Yes, there are several other factors that can affect the maximum distance of a lit power source. These include the quality and cleanliness of the power source, any obstructions or reflections in the path of the light, and atmospheric conditions such as humidity and air density. It is important to consider and account for these factors when conducting experiments to find the maximum distance of a lit power source.

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