How long will it take, after the switch is closed, for the capacitor to charge to 80% of the battery voltage? The initial voltage on the capacitor is 0V.

Your phone died. Again. In these scenarios, who among us has not dreamed the dream of a future where our devices charge instantly and last forever. As capacitors—or even more exciting, ultracapacitors ...

The batteries we rely on for everything from our cars to our cell phones use a chemical reaction to store and release an electrical charge. The chemicals involved force a large number of tradeoffs in ...