Posted by Don on .
An electric immersion heater is rated 5 A when connected to a 120V circuit. What is the resistance of the heater? If it takes 168 KJ to heat 500 ml of water from 20 deg C to boiling, how long does it take to heat the water?

Physics 
drwls,
R = V/I = 24 ohms
Power = V*I = 600 J/s
600*t = 168,000 J
Solve for t in seconds