5.1 Voltage, Resistance, and Current
5.2 Ohm's Law Formula
1. "Power is the rate of doing work" (66), the amount of work done by the electricity (in this case) in a given time. We might express this relationship with the formula:
P = W/T
Another way to put it is to say that electrical power is the rate of converting electrical energy into some other form of energy (e.g., heat).
2. Electrical power is measured in watts (watts having the symbol w). A 100 watt bulb burns brighter, has less resistance, and dissipates more power than a 60 watt bulb.
3. Power equals voltage times current P = EI .
- If we substitute in E = IR from the previous lesson, we get P = I2R .
- We can also do a little algebra and come up with P = E2/R
- You use different versions of the relationships depending on what information is given.
The section doesn't really explain what work is when it comes to electricity. I guess that is something for a later module. In terms of mechanical energy, work is the force times the distance. I am not remembering exactly how that plays out with electricity, but I seem to remember that the same unit of work is used, the joule.