How do computers and electronics produce heat?


How do computers and electronics produce heat?

In: 7

Electricity is warm, and electronics are a maze that electricity runs though. Computers are very intricate mazes with lots of paths being used at once. People are happier when their electronics and computers are small so they push the paths closer and closer together, concentrating the warmth and limiting opportunities to cool down.

The metals and semiconductors within each part have resistance to electrical current which is necessary to operate. That resistance changes electrical energy into thermal energy, light, sound, etc.

Electrical components have resistance. If elecrons flow through them, a part of the energy is radiated as heat due to resistance.

The heat is from the the electrons in the electric current encountering resistance along the way. It’s similar to rubbing your hands together – you apply force (like the electrons being driven by a voltage) but the friction in your hands resists the movement and there’s heat produced as a result, because the energy has to go somewhere.

Electricity what we call it when electrons move through something, like a wire or the circuit in a computer. When it moves through those different things, it might have a smooth ride. A big wide flat street with no traffic. It just zooms through. But sometimes that street is (intentionally) rougher or full of other things. This makes it harder for the electron to move down the road. It bumps into things. Maybe it has to squeeze through the crowd. All this bumping and pushing takes effort (or energy) and it makes heat.

In your computer or anything electrical, no road is perfect. Heat is always made. An electrical stove is the purest example of this. All its electricity is turned into heat in the form of that glowing red coil.

As an aside, if you’ve heard the term superconductor, that is a perfect road. The electron doesn’t even have to walk down it. It floats effortlessly on its way. It has zero resistance. The electron doesn’t bump into anything.

If you pass electricity through a piece of conductor, it is going to produce some heat because of the resistance. Same is the case with computers.

Wires have resistance. That means they heat up whenever electricity flows through them.

A computer basically implements 0’s and 1’s using a huge number of switches. Basically all modern computers wire their switches using the “CMOS logic” strategy, which stands for “Complementary MOS.” MOS describes what the switch is made of (Metal Oxide Semiconductor). Complementary means every point in the circuit that represents a 0 or a 1 is wired to a pair of switches which connect directly to the – and + terminals of the power supply. If the point is supposed to be a 0, the first switch connects it to the – terminal and the second switch disconnects it from the + terminal, and it’s 0V. (The reverse happens if the point is supposed to be a 1, and it takes the + terminal voltage; traditionally 5V, but usually 3.3V or lower in newer devices).

If you draw a CMOS circuit on paper, it looks perfectly efficient because the power supply terminals are never connected to each other, so no current flows and there’s no way for it to heat up. Unfortunately the paper drawing makes a few assumptions that don’t apply to switches and wires you can build in the real world with tools and materials we have:

– (1) Real switches can’t switch infinitely fast.
– (2) Real switches sometimes act “half-open half-closed” while they’re switching and let electricity through.
– (3) Real switches sometimes let a tiny bit of electricity “leak” through even when they’re “supposed” to be fully open, and this problem gets worse the more you try to make the switches small and fast.
– (4) The sections of wire you’re trying to use as points that represent 0 or 1 have non-zero “capacitance,” basically you don’t change voltage just by being connected to a power supply terminal; the power supply needs actually to push or pull a few electrons into or out of the metal to actually change its voltage.
– (5) The wires you’re using have non-zero “inductance,” basically there’s a sort of “momentum” and you get energy wasted by the electronic equivalent of [that sound pipes sometimes make when you shut off a faucet](
– (6) The wires have non-zero resistance so all these currents cause stuff.

Think for a minute about your phone. It’s about a billion switches, switching about a billion times a second, jammed in a tightly packed case with no fans or wide-open paths to create airflow, the case is made of plastic (an insulator) and placed in a cloth pocket (another insulator), right next to a warm human — It’s a *freaking miracle of engineering* that your phone doesn’t melt itself.