Power Distribution In Parallel Circuits:
Whenever resistances are wired in parallel, they each consume power according to similar formula, P = I2R. Though, the current is not similar in each resistance. A simpler technique to compute the power Pn dissipated by resistor of value Rn is by using the formula Pn = E2/Rn, here E is the voltage of the supply. This voltage is similar across every resistor. In a parallel circuit, the whole power consumed is equivalent to the sum of the wattages dissipated by separate resistances. This is, however, true for any dc circuit having resistances. Power cannot come out of nowhere, or can't be disappear.
PROBLEM:
A circuit have three resistances R1 = 22 ohms, R2 = 47 ohms, and R3 = 68 ohms, all in parallel across a voltage E = 3.0 V. Compute the power dissipated by each resistor.
SOLUTION:
Firstly, find E2, the square of the supply voltage: E2 = 3.0 x 3.0 = 9.0. Then P1 = 9.0/22 = 0.4091 W, P2 = 9.0/47 = 0.1915 W, and P3 = 9.0/68 = 0.1324 W. These must be rounded off to P1 = 0.41 W, P2 = 0.19 W, and P3 = 0.13 W, correspondingly.