18Power: And Work
18.1 Introduction
In this chapter, we will examine several types of electric power.
18.2 Electric Power and Work
Electrical potential is energy and all kinds of energies can create work.
The energy contained in one liter of diesel, for example, can be converted by a machine into mechanical movement or other kinds of work.
The work produced by a car or a tractor, for example, can be measured in Joules. In terms of electrical circuits, work or power is generally measured in Watts.1
Electric power is a physical quantity that measures the work produced in a period of time.
An industrial electric oven, for example, has a power greater than a domestic oven because it can produce more work, in that case, heat, in the same amount of time.
Electric power, current, and voltage are related by the following formula.
18.3 Powers in Parallel
Consider the circuit shown in Figure 18.1.
Figure 18.1 Power in parallel.
Both resistors are in parallel with a 12 V battery and draining a total current i from it. This current splits into i1 and i2 that flows across R1 and R2, respectively.
Power can be found by using
But Ohm's law states that
If we substitute this ...
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