Equivalent resistance for 2 resistors in parallel:

$\overline{){{\mathbf{R}}}_{{\mathbf{eq}}}{\mathbf{=}}\frac{{\mathbf{R}}_{\mathbf{1}}{\mathbf{R}}_{\mathbf{2}}}{{\mathbf{R}}_{\mathbf{1}}\mathbf{+}{\mathbf{R}}_{\mathbf{2}}}}$

Equivalent resistance for resistors in series:

$\overline{){{\mathbf{R}}}_{{\mathbf{eq}}}{\mathbf{=}}{{\mathbf{R}}}_{{\mathbf{1}}}{\mathbf{+}}{{\mathbf{R}}}_{{\mathbf{2}}}{\mathbf{+}}{\mathbf{.}}{\mathbf{.}}{\mathbf{.}}{\mathbf{+}}{{\mathbf{R}}}_{{\mathbf{n}}}}$

Ohm's law:

$\overline{){\mathit{i}}{\mathbf{=}}\frac{\mathbf{V}}{\mathbf{R}}}$

Power:

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

The 40Ω and 10Ω resistors are in parallel.

They are all in series with the 4.0Ω resistor.

R_{eq} = 4.0 + (40)(10)/(40 + 10) = 12Ω

From Ohm's law, current, i = V/R

Determine the power dissipated by the 40 ohm resistor in the circuit shown. (the values from left to right at 4.0 ohm, 40 ohm, 10 ohm, 18V)

Possible answers are

1. 9.0 W

2. 27 W

3. 4.5 W

4. 3.6 W

5. 14W

Please show your work.

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Power in Circuits concept. You can view video lessons to learn Power in Circuits. Or if you need more Power in Circuits practice, you can also practice Power in Circuits practice problems.