Question

The heating element of an electric oven is designed to produce 3.9 kW of heat when connected to a 240-V source. What must be the resistance of the element?5)A 120-V hair dryer has two settings: 950 W and 1400 W .a) Determine the resistance at 950 W setting.b) Determine the resistance at 1400 W setting.

Answer 1

Explanation:

For a linear resistor, the power, voltage and resistance are related by

$P=\frac{V^2}{R}$

$3900=\frac{240^2}{R}$

$R=14.77\text{ Ohm}$

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$P=\frac{V^2}{R}\implies R=\frac{V^2}{P}$

$\text{a) }R=\frac{120^2}{950} = 15.157\text{ Ohm }$

$\text{b) }R=\frac{120^2}{1} = 10.286\text{ Ohm }$