I am in the middle of trying to wrap my head around basic electronics. I understand the concepts of voltage, amperage, and resistance, however I'm confused about how heat is generated and related to these three things. These are my assumptions and questions:
When you plug an appliance into a 120 V wall outlet, some amount of amperage will run through the wire depending on the amount of resistance in the circuit (I=V/R, where the voltage is a constant 120 V). Resistance in the circuit depends on the material resistivity and the length/shape of both the wire and appliance.
The difference between a high amperage appliance (like a refrigerator or space heater) and a low amperage appliance (like a light bulb) is the resistance in the circuit. A light bulb draws less amperage because there is more resistance. In other words, resistance is used to control the amperage drawn by an appliance. The appliance is intentionally made to have the right amount of resistance so as to draw the right amperage.
- Is this assumption correct?
More resistance creates more heat. This is due to the electrons bumping into the atoms in the material they are moving through. I kind of envision this as being like having more friction, so therefore more heat. This is the reason a frayed wire can heat up and cause an electrical fire.
- Does this mean that since a light bulb has more resistance than a space heater, it is more likely that it can heat up and cause an electrical fire? Are small appliances therefore more dangerous than large appliances due to their higher resistance?
- Does current in itself create heat? So when you reduce resistance and therefore increase current, does more heat get produced (although heat due to resistance decreases)? Conversely, does increasing resistance (e.g. fraying a wire) also help it cool down since current is reduced?
Any explanations would be greatly appreciated.