Question

A 120-V hair dryer has two settings: 850 W and 1550 W .

B) Determine the resistance at 850 W setting.

C) Determine the resistance at 1550 W setting.

Answer 1

power $P=\frac{W}{t}=\frac{vq}{t}$

P=vi $\left (i=\frac{q}{t} \right )$

$P=\frac{v^{2}}{R}\left (\therefore i=\frac{v}{R} \right )$

we know v=120 V

b)resistance of hair dryer at p=850 W

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

$R=\frac{120^{2}}{850}$

=$16.94\Omega$

c)resistance of hair dryer at 1550 W

$R=\frac{120^{2}}{1550}$

=$9.29 \Omega$