Tagged Questions
2
votes
1answer
78 views
Question on Radiance equation
The radiance equation is
$$
L = \frac{d}{dA} \frac{2(\phi)}{dW cos(\theta)} (watt/srm^2)
$$
where $\phi$ is the flux.
I am thinking, should not be the cosine term on the numerator instead of the ...
0
votes
1answer
1k views
Why are umbrellas black?
Why are umbrellas specifically in black? Of course we do have colored ones, but black is the majority. Is there any scientific reason behind it?
1
vote
0answers
47 views
Light vs. X-ray interactions with Phosphor
Looking for some information on how light and xrays interact with phosphorous, or what might cause the following:
Scenario
A focus beam of light is directed at a phosphor plate at the same time as ...
2
votes
2answers
161 views
Is there a reason for photodynamic therapy to not cause cancer if mobile phones might?
I don't want to open a debate about whether cell phones can cause cancer,
I read the thread: Could cell-phone radiation cause cancer?
For the sake of this question let's assume there's a chance for ...
0
votes
2answers
265 views
Do and can phone signals come inside AC car which is glass-packed
Can phone signals penetrate glass, so can I expect phone signals to come if I am sitting inside a closed AC car.
Thanks,
