How does the current flow in one direction if the electrons are hoping back and forth? Shouldn’t the net current be zero?
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The net current *is* zero. But power isn’t transferred by current going from the battery to an item like a lamp, it is transferred by the electrons being forced to move through the lamp. The lamp doesn’t care which direction the electrons are flowing in.
Think about a bike chain. When you pedal the wheel turns because the chain connects your feet to the wheel. If you keep changing direction the wheels would spin one way and then the other. You don’t have to give energy to one part of the chain and then wait for it to get to the wheel. As soon as you pedal the wheel moves. Only in this case if you are pedalling one way and then the other, the bike wouldn’t go anywhere. But there would be constant energy transfer between you and the wheel. This is what is happening in an ac supply. The electrons go back and forth and as they do this in your appliances they transfer the energy to the appliance.
If you want to go slightly more advanced, what matters is the power transfer not just the current, which goes like the current squared. Current squared is always positive so there is always energy transferred if current is flowing. Over one cycle the current created by a generator, which is like a sin wave, has an average of zero, while the current-squared has an average of 1/2 of the peak current in the cycle. This leads to the idea of the mains voltage, which is actually 1/(root2) times the peak voltage. It is the equivalent dc supply that would convert the same energy each second.
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