Power in Circuits Video Lessons

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# Problem: The heating element of an electric dryer is rated at 4.1 kW when connected to a 240 V line. (a) What is the current in the heating element? Is 12-gauge wire large enough to supply this current? (b) What is the resistance of the dryer's heating element at its operating temperature? (c) At 11 cents per kWh, how much does it cost per hour to operate the dryer?

###### FREE Expert Solution

Power:

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

Energy:

$\overline{){\mathbf{E}}{\mathbf{=}}{\mathbf{P}}{\mathbf{·}}{\mathbf{t}}}$

(a)

P = 4.1kW (1000W/1kW) = 4100 W

V = 240 V

I = P/V = 4100/240 = 17.08 A = 17.1 A

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###### Problem Details

The heating element of an electric dryer is rated at 4.1 kW when connected to a 240 V line.

(a) What is the current in the heating element? Is 12-gauge wire large enough to supply this current?

(b) What is the resistance of the dryer's heating element at its operating temperature?

(c) At 11 cents per kWh, how much does it cost per hour to operate the dryer?