Power in Circuits Video Lessons

Concept

Problem: In the circuit of the figure (Figure 1), each resistor represents a light bulb. Let R1 = R2 = R3 = R4 = 4.43 Ω and let the EMF be 9.01 V. a. Find the power dissipated in the bulb R1.b. Find the power dissipated in the bulb R2.c. Find the power dissipated in the bulb R3.d. Find the power dissipated in the bulb R4.e. Which bulb or bulbs glows the brightest?

FREE Expert Solution

Power:

$\overline{){\mathbf{P}}{\mathbf{=}}{{\mathbf{i}}}^{{\mathbf{2}}}{\mathbf{R}}}$

The total current drawn from the battery is given by:

$\overline{){\mathbf{i}}{\mathbf{=}}\frac{\mathbf{V}}{{\mathbf{R}}_{\mathbf{e}\mathbf{q}}}}$

Resistors, R2, R3, and R4 are in parallel.

$\begin{array}{rcl}\frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{234}}}& \mathbf{=}& \frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{2}}}\mathbf{+}\frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{3}}}\mathbf{+}\frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{4}}}\\ \frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{234}}}& \mathbf{=}& \mathbf{=}\frac{\mathbf{1}}{\mathbf{4}\mathbf{.}\mathbf{43}}\mathbf{+}\frac{\mathbf{1}}{\mathbf{4}\mathbf{.}\mathbf{43}}\mathbf{+}\frac{\mathbf{1}}{\mathbf{4}\mathbf{.}\mathbf{43}}\\ \frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{234}}}& \mathbf{=}& \frac{\mathbf{300}}{\mathbf{443}}\\ {\mathbf{R}}_{\mathbf{234}}& \mathbf{=}& \frac{\mathbf{443}}{\mathbf{300}}\end{array}$

R234 = 443/300

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Problem Details

In the circuit of the figure (Figure 1), each resistor represents a light bulb. Let R1 = R2 = R3 = R4 = 4.43 Ω and let the EMF be 9.01 V.

a. Find the power dissipated in the bulb R1.

b. Find the power dissipated in the bulb R2.

c. Find the power dissipated in the bulb R3.

d. Find the power dissipated in the bulb R4.

e. Which bulb or bulbs glows the brightest?