Thermodynamics

[pyroglycerine]

I have a couple of questions,

 

Moderators: If it's in the wrong category, go ahead and change it, please don't ban me.

 

If you set the background of a computer screen black, would it lose less energy than if it were white?

 

If you were to place a cover over the screen so that light cannot escape, it would transfer to heat energy correct? Please could somebody explain to me the process of the transformation of light energy to heat energy?

 

Thanks,

[Enthalpy]

Hi Pyroglycerine, welcome here!

 

A CRT monitor (the old monitors that were as thick as wide) consumes less power when it produces less light, for instance if most background is black. It directly modulates the intensity of its electron beams (three to make colours) to produce more or less light. The difference isn't huge.

 

All LCD monitors produce the colours and shades by the controlled opacity of each colour of each pixel, so a black background would consume as much light hence electricity and stop more light at the LCD. But some LCD monitors adjust the light intensity emitted behind the LCD when you adjust the monitor's display brightness, so dimming these monitors reduces the electricity consumption. Simplifying: LED-lit LCD do adjust the emitted power, while fluo-lit adjust the opacity of the LCD.

 

Plasma screens adjust the light emitted by each colour of each pixel, as do LED screens. Though, I know them for TV sets, not for computer monitors.

 

A mundane cover would absorb light emitted by the monitor and convert it to heat. Many detailed mechanisms exist; they boil down to electrons in the cover being shaken by the photons, and their movement transferred in a disordered way to all the matter.

 

From my experience on the present forum, a wrong category won't let moderators ban you... In case you've been traumatized by Phy...ums before, this is a normal place here, much more pleasant thanks to them.

[pyroglycerine]

Thank you for your informative, useful answer!

Yes, I have previously been banned, well, rather I left the Phy...ums for that very reason.

I was also banned from the chem...ums with no explaination whatsoever. As far as Im aware I only ever made one post there..

Anyway, great forum here!

Thanks again!

[Sensei]

Displays used by modern devices such as ebook are using energy only to switching states. If pixel has the same color/brightness as in previous, it uses no energy.

[pyroglycerine]

My apologies for the irrelevance of this post to the thread topic.

 

Dear Enthalpy from the chemicalforums,

 

Each and every time I go to the website it says 'Sorry guest you are banned from using this forum. This ban is not set to expire.' So yes,I am led to believe I am banned from using your forum. If you can fix this, please pm me on this forum or email me so as not to disrupt the thread any longer. When you emailed me you did not leave a means of giving you a direct reply.

 

Thank you.