Download 1) Madge`s 180 watt curling iron is plugged into a 120

Electrical Power
Name ___________________________________________
1) Madge's 180 watt curling iron is plugged into a 120-Volt wall outlet.
a) What current does the curling iron draw?
b) What is the resistance of the iron?
c) Come up with an equation for power that has voltage and resistance, rather than voltage and current.
2) A tea kettle (heating coil R = 125 Ω) plugged into the wall (120 V) is used to bring 210 ml of water from 24oC to a
boil at 100oC.
a) Compute the current in the coil.
b) Compute the rate at which electrical energy is delivered. ("Rate" is "something per time", so "rate of energy
delivered" is energy per time. The question asks you to computer the electric power of the tea kettle.)
c) 4190 J of heat energy are required to raise the temperature of 1 kg of water by 1oC. How much heat energy is needed
to raise the temperature of 210 ml of water (= 210 g) from 24oC to 100oC? [Ans: 6.69x104 J]
d) Assuming the kettle's heating coil is 100% efficient -- assuming that all the electrical energy is converted to thermal
energy -- compute the time needed to bring the water to boiling temperature. [Ans: 580 s]