why does the resistor became hot ? answer in one sentence
Answers
Answer:
Overheating of Resistor
When a resistor is placed under a voltage that approaches the upper limits of its power rating, the resistor generates more heat than normal. This is due to the voltage attempting to force more current (electrons) through the resistor than it is designed to pass.
Explanation:
A simple answer is because they dissipate power - they have to, because otherwise they wouldn’t be resistors. A resistor is defined by Ohm’s Law, which states that V= IR, so a current flowing through a resistor HAS to cause a voltage to be developed across it. And we also know that power = V x I, so a current flowing through a resistor MUST dissipate power. The only way that power can manifest is as heat.
But WHY is that?
The true cause is because of quantum physics. Electrons in a resistor are bound to their parent atoms. They are bound more tightly than they are in conductors like copper metal, though copper also has some resistance, but more loosely than in an insulating material. The electric field potential across the resistor forces electrons to move - the negatively charged electrons are repelled by the negative potential at one end of the resistor and attracted to the positive potential at the other. As they move, they will be forced to leave the outer orbits of their parent atoms, which absorbs a little energy, and then they fall into the orbits of other atoms they pass, releasing the same little bit of energy. The energy is absorbed and released as photons, though with low energy. The photons are emitted from the resistor as infra-red radiation, a.k.a heat.