Problems

Does more electric charge flow out of a battery or into a battery when it is in use?
What is the sign of the net electric charge on the current carrying wires in your home?
What happens to the electrons in a wire as they pass through a light bulb (or any other electrical device)? That is, what changes as electric current flows through a circuit?
What is the source of the electrons in an electric current flowing through a circuit?
Household electrical outlets provide a potential difference of 120 V. Nevertheless, one should never touch bare wires or continue to use damaged electrical equipment. The risk of death is just too great. A typical big Van de Graaff generator used for classroom demonstrations provides an electric potential of about 400,000 V. It makes impressively large sparks that hurt like hell, but it will not kill you. This seems like a contradiction. Why doesn't the higher voltage of the Van de Graaff generator come with a higher risk of death? (There are two factors at work here.)

An average human brain has a power consumption of about 20 W.
1. How much charge does the brain move every second as the neurons switch from resting potential (−80 mV) to action potential (+40 mV)?
2. Would you blow a fuse if you wired your brain into a 20 A circuit in a typical North American home?
3. Movie trivia question: Could you power The Matrix using humans as batteries?
The magnitude of the electric field needed to produce a spark in air (its dielectric strength) is about 3 × 10⁶ V/m. As Benjamin Franklin showed in his famous experiment of 15 June 1752, lightning is basically a very, very large spark. A good sized bolt could travel 1 km and transfer 1000 C of charge in half a second.
1. What voltage is needed to make a typical lightning bolt?
2. How much current flows along its jagged path?
3. How much energy does it deliver?
4. What is the power of a lightning bolt?
5. Movie trivia question: Could you power a "flux capacitor" with a lightning bolt and go Back to the Future?