I've known that resistance emits heat, but what is the purpose of converting electricity to heat on a circuit board?
For 99.99% of electronics, there is no
purpose in converting electricity to heat. In fact, heat is the
Number 1 enemy of electronics.
It occurs as a natural by-product in just about every aspect of electronic circuitry. A fact that we all lament at one point or another.
Resistors have, perhaps, the highest profile in this regard because of the way they function ... which brings them straight into the realm of Ohm's Law.
One key objective in any circuit design is to minimise the amount of heat generated - and this is done for a number of reasons....
- Wasted energy: Why pay for a bucketful of electricity when you only need a cupful to do a job?
- Equipment size and cost: Why build a power supply to deliver 10 amps when a more efficient circuit can do the job with 1 amp?
- Cooling considerations (again, size and cost): Why build something that requires fan forced cooling and a big heatsink when an efficient design can get away with passive cooling?
- Compactness of circuitry: low heat emissions means you can pack more circuitry into less space. A classic example why this is great is the computer - and in particular, integrated circuits like a CPU.