Question

A dual voltage/dual resistance AC hair dryer can be used with a 120 V or 230 V power supply. A switch allows the user to set the voltage (and hence the resistance) to the appropriate value. A tourist takes her 1530 W dual voltage hair dryer to Europe. She forgets to set the switch to 230 V. What power does the hair dryer consume before it starts to smoke?____________ W

Answer 1

The power is
`p= 5621 W`

Step-by-step explanation:

In order to obtain the power it consumes we need to first obtain the resistance of the hair dryer at 120 V

`R = (V^2)/(P) = ((120 V)^2)/(1530W) = 9.411 \Omega`

Now the power supplied in Europe at their voltage of 230V would be

`P = \frac{V^2} {R} = ((230V)^2)/(9.411 \ \Omega) = 5621 W`

Looking the power obtain we see that it is higher than 1530 W so this would cause the dryer to smoke.