Distance from light(or other electromagnetic)source

  • Thread starter slyth
  • Start date
  • #1
2
0
Hello.I'm doing a research on ultraviolet (mainly on UVB band).
UVB band with the wavelength 280nm~315nm has the energy of 4.43eV~3.94eV
which can be calculated from Plank-Einstein equation.

In visible spectrum,light intensity can be calculated from
[tex] E_{r}=\frac{E_{0}}{4\pi r^{2}} [/tex]
With the above equation,when E(r) and E(0) is known,distance,r can be calculated.
Light radiation is measured in mW/cm^2,and I right?

So,my question is,using the above equation,instead of light radiation,
is it possible to calculate distance by replacing E(r) and E(0) with energy [eV] ?
Where E(r) and E(0) can be obtained from UV sensor readings.



Radiometers do measure UV intensity in mW/cm^2. I'm trying something different.
 

Answers and Replies

  • #2
HallsofIvy
Science Advisor
Homework Helper
41,847
965
Yes, of course, that's a simple algebra calculation.

Multiply both sides of the equation by [itex]r^2[/itex] and divide both sides by [itex]E_r[/itex] to get
[tex]r^2= \frac{E_0}{4\pi E_r}[/tex]
Now take the square root of both sides:
[tex]r= \sqrt{\frac{E_0}{4\pi E_r}}[/tex]
We use the positive root because distance is always positive.
 

Related Threads on Distance from light(or other electromagnetic)source

Replies
1
Views
1K
Replies
26
Views
121K
Replies
12
Views
6K
Replies
2
Views
891
  • Last Post
Replies
4
Views
618
Replies
3
Views
729
Replies
25
Views
3K
  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
4
Views
2K
Top