4
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Why is infrared used in thermal imaging and not microwave or radio wave or ultraviolet?
Because the heat is given off in the infra-red portion of the electro-magnetic spectrum.
That the effects or properties change with frequency change enables us to look at the different things.
You can ...
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4
votes
Accepted
Blackbody radiation
Your assumption is incorrect. The color we see is the combination of reflected light, if any, and radiated light. All objects radiate photons of one wavelength or another. All objects absorb ...
- 4,259
3
votes
Accepted
Protect equipment against electromagnetic radiation
There are 2 effects to look out for:
Magnetic induction into wiring from e.g. coronal mass ejections. The electrical grid is already largely protected against these events. To protect equipment in ...
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2
votes
Radioactive Materials to Energy AT HOME
Attempting this as a home experiment is unlikely to be feasible.
https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#241Am gives the efficiency of professional prototype designs using ...
- 12.6k
2
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Melt plastic powder bed with radiant heat?
Any diameter wire, multiple parallel heated elements describes a toaster, an electric oven, any number of radiant heaters already in existence.
Your problem is not whether you can do it with such a ...
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2
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How to consider the dimension of a cylinder when computing its radiative budget?
You certainly need to take account of the shape of the object somehow.
As a simple example, consider a sphere of radius $r$ in space where everything except solar radiation can be ignored.
The cross ...
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2
votes
Can cables and wires for home internet emit harmful radiation?
From Wikipedia:
Ionizing radiation is generated through nuclear reactions, nuclear decay, by very high temperature, or via acceleration of charged particles in electromagnetic fields. Natural sources ...
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1
vote
Strange units with UV water disinfection systems
Re: surface are vs volume -- the absorbance will depend on the liquid you are sterilizing (turbidity, the absorbance spectrum, thickness, the extinction coefficient of the chemicals in your liquid etc)...
1
vote
Strange units with UV water disinfection systems
The formula shown is: UV Dose = UV Intensity x Retention Time
Intensity is power per surface area ($W/cm^2$) and retention time is time (seconds). In other words how long the medium is exposed ...
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Can cables and wires for home internet emit harmful radiation?
Like others have stated, low intensity non-ionizing electromagnetic radiation (the radiation from wires in your home) has no known health effects. That said, it does not hurt to minimize EMI as it ...
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Can cables and wires for home internet emit harmful radiation?
There are known risks from high intensity electric fields. For example see the UK legislation "The Control of Electromagnetic Fields at Work Regulations
2016" at https://www.legislation.gov....
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1
vote
Trapping sun heat the most - greenhouse
Greenhouses generally work by trapping radiation (infrared to be more specific). More specifically what they do is allow most of the sun radiation to come through and then trap the infrared radiation ...
- 24.3k
1
vote
Can air be ionized using microwaves?
Microwaves are not "ionizing" in that they will not knock electrons, protons, or neutrons out of orbit or split an atom with their energy via particle collisions. This is in contrast to high-...
- 7,148
1
vote
Accepted
Calculate FTIR-system response functions from measurements of a calibrated black body
For anyone coming later:
I ended up using a procedure described here:
Kevin C. Gross, Phenomenological model for IR emission from high explosive detonation fireballs
In one sentence: I ended up ...
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1
vote
What emits more radiation, cell network or wifi?
So, after a little googling around.
Cellphones typically transmit on 3/4 G at between 0.3 and 3 W - subject to tower location & interference. The out put power is managed by the cell tower.
...
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1
vote
calculating the efficiency of a microwave oven
The equation for efficiency in thermodynamics is as follows:
$$\eta = W_{out}/W_{in}$$
and to get this as a percentage you just multiply $\eta \;\mathrm{x}100=\%$
See the link below!
https://en....
- 11
1
vote
Epoxy that can withstand up to 800C and is optically transparent?
You will need to go for glass and casting.
High temp silicones and epoxies don't go to 800 deg C and they are not clear anywhere near their high temperature variants. Closest I know is a murky clear &...
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1
vote
Accepted
Radioactive Materials to Energy AT HOME
Depending on how much nuclear material you have, you can use a system based on thermoelectric materials to directly use the heat from the decay of the material to generate electricity. Following from ...
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1
vote
Accepted
Heat Transfer coefficient calculation for hot air flow inside rectangular duct
There are several issues going on that I believe are making the model not very accurate. They all in some way relate to your question about the convection:
Breaking up the flow into 5 discrete chunks ...
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