Can we create any electrical equipment which works in the opposite way to a bulb, such that is whilst it is switched on all the light in the surrounding area gets absorbed creating darkness?
Maybe possible in theory, but not plausible with any foreseeable technology.
Light is a torrent of electromagnetic waves. Darkness is the absence of any such light waves.
You can cancel out a wave by creating a wave which is exactly identical but with the phase shifted by 180°. This is called "destructive interference". But there are a couple of problems with trying to cancel out a light source in a real-world scenario:
if your two wave emitters (light and "anti-light") are not in exactly the same location, then the interference only works in one spot at a time.
then there is the problem that light is usually not just a wave with one frequency but a combination of multiple waves with lots and lots of different frequencies and amplitudes (that's what defines the color of a light). If you want to cancel out a light source, you need to match all those frequencies.
And then there is the problem that in a regular lighted situation you don't have one light source but many different light sources as well as indirect light. So you don't have the same combination of light waves on every surface.
So you can not just have an anti-lightbulb which you can switch on anywhere and expect to work. You would have to know exactly which micro-meter of surface in the surrounding receives which light frequencies and then send out rays of light with exactly those waves so that they arrive phase-shifted by 180°. This would not just require a tremendous computing power but also the ability to emit billions of unique rays of light with an extremely fine precision.
If you want to prevent people from seeing something, then there are simpler methods.
- You can obstruct their view with smoke or fog.
- You can temporarily blind them with a strong flash of light.
- You can obstruct or disable any sources of light.
That already exists.
It's called a smoke bomb.
If you stick your head into it the smoke, you won't be able to see s... a thing.
If you make the smoke black, it will absorb visible light in all wavelengths. If you use vantablack, your absortion efficiency goes all the way to 99.96%.
Going laterally a bit here.
If all you need for your "darkness" is for people not to be able to see anything, then your device could generate some (unobtanium-based) E-M wave pattern which completely shuts down the optic nerve.
Obviously this will be useless if your intent is to stop hardware such as video cameras from recording information.
Based on answers above, two options:
High-tech smoke bomb, namely a cloud of nanobots that stay in a given area, fill the air in it evenly, are painted with Super-black paint. In fact, rather than microscopic nanobots, make them more like moths or floating flakes. Device coordinates nanobots and provides energy through induction: nanobots constantly circulate to the device to recharge, and then away from it to dim the furthest corners.
Brute force: device emits super-bright light that makes it impossible to see anything, by overwhelming both retinas in the eyes and sensors in cameras. Device will need a lot of energy, and a very efficient light bulb. Can make it a plot point that it does not last long.
Although it's counter to every sci-fi show that I've ever seen, wouldn't a shield that blocks lasers also block physical light?
That would make it easy to turn on a shield emitter lightbulb and have it block all the light from entering an area. I'm not sure if it would stop light created in that area.