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Question

The resistance of a bagel toaster is 18 . To prepare a bagel, the toaster is operated for one minute from a 120-V outlet. How much energy is delivered to the toaster?

Answer 1

You haven't mentioned a frequency in this problem, so I'm assuming the problem wants us to treat this as a DC circuit problem. If this is wrong, post a followup and I'll do this problem as an AC circuit. Explaining how to calculate power and energy in an AC circuit much more complicated than doing the same with a DC circuit.

Power is equal to current times voltage.
P = I * V

Voltage = Current * Resistance (ohm's law)
V = I * R

I = V / R
P = V^2 / R

P = (120 V)^2/(18 ohms) = 800 W

One watt is one joule per second (J/s)

800 W * 60 s = 48,000 J

48,000 J is delivered to the toaster.