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Emissivity of the black body is 1. And this is probably the reason that the condenser of refrigerator is painted black to loose heat efficiently by radiation ,though there are other modes of heat transfer like conduction and convection which is not affected by colour of the body
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What is the correct CSS for adding a background image to a page?
Use the attribute BGCOLOR=".." inside the start Body tag using the color you want as the value. It should look like this: this will give you a black background, and at the end of your HTML document you close the Body Of cause if you use a black background you cannot use black font. You won't be able to see it. You can set the value=".." of the background to what ever you like.
Who was the first Black person to invent Technology?
No single person black, white, yellow or green invents technology. Technology is a body of knowledge added to by individuals and groups. Sometime it is known who added a part of that knowledge and when they did so. At other times is is not known, especially very early additions.
What attibute you use in the body tag to give the background a solid color?
You use the style attribute to add any presentation to your BODY element, including background-color. This is the code to make an HTML document with a red background. <body style="background-color: red"> You can also add a stylesheet to the head of the document (or an external file, if you're going to have the same rules on more than 1 page.) <style type="text/css"> body { background-color: #f00; } /* Short of ff0000 which is hex for "red" */ </style>
Was John lee love black?
yes, john lee love was black his father was white and mother was black so yes he was black
What difference is there between black patent and black PU colour?
black patent is the really shiny one, whereas the black pu is the dull, unshiny looking one
What is the definition of 'emissivity'?
The term "emissivity" refers to the relative power of a surface to emit heat by radiation. It could also be defined as the ratio of energy radiated by a particular material to energy radiated by a black body.
How does a silver surface work in radiation?
The concept involved here is Emissivity - the ability to emit energy. e is the usual symbol, and a perfect emitter would have an e of 1. Your perfect black body will have this emissivity of 1.A highly polished surface (polished at all the wavelengths concerned) will have an emissivity much smaller. Polished silver has an emissivity of about 0.02.In general the emissivity of a surface is inversely related to its reflectance, but this does vary with the surface finish, colour, and the mass of the object.It is worth noting, that low emissivity glass is used with effect in the double glazing of windows.
What is the emissivity of silicon?
the emissivity of Si is 0.6
What is the emissivity of an ideal reflector?
The emissivity is 0...
The wavelength of the radiation emitted by a body depends upon?
Temperature and emissivity of the body.
Do reflector panels have high or low emissivity?
low emissivity
A material with zero emissivity radiates to other body in vacuum or not?
Zero emissivity means generally no radiation for the far-field. However, for the near-field case, energy may flow to another bodies.
Why is Ice a black body?
It's not. The term "black body" is used to describe a hypothetical perfectly black object that reflects no light at all .here the light refers to entire electromagnetic spectrum. Although the emissivity of ice is near about 0.95 hence it behaves more as black body (emmisivity = 1) than a white body. The reason is for ice to be near about black body is that ice is a very good absorber of radiation outside the visible region (eg for infrared rays ) . Hence ice is more a black body than a white body (as in appearance ).
Why heat sinks are black anodized?
Radiative heat transfer (heat transfer by electromagnetic radiation) is proportional to e*(T1^4 - T2^4) where T1 is the absolute temperature of the material, T2 is the absolute temperature of the surroundings, and e is the emissivity coefficient. A black material has a high emissivity coefficient, while a silvery material has a low emissivity coefficient. However, the emissivity coefficient cuts both ways, so to speak. A black material in thermodynamic equilibrium with its environment absorbs more radiation, true. But it also emits more radiation (this is necessary for equilibrium to hold). Likewise, a silvery material absorbs less radiation, and also emits less radiation. Conductive heat transfer ensures that the black material on the surface of the heat sink remains hot. The surroundings are at a lower temperature. Therefore T1 and T2 are set, and the heat transferred from the heat sink to the surroundings is simply proportional to e, the emissivity coefficient.
Is emissivity a property of a material?
Yes
What is normal spectral emissivity?
Normal is equal to vertical.Flat object radiates light and heat to hemisphere space.Sometimes,it is convenient to measure the vertical direction.Hemisphere spectral emissivity ε and normal spectral emissivity rate εn have a relationship: ε =Mεn, M is correction factor.
What is photo emissivity?
Emissivity of a surface is defined as its effectiveness in emitting thermal radiation. The term photo emissivity is likely used to narrow the focus to emitting visible light.
