What is a battery?

• A. A single cell that stores chemical energy.
• B. A device made up of two or more cells, where electric potential increases for each cell present.
• C. A device that converts kinetic energy into electricity.
• D. A device that measures electrical current.

Answer: (B)

A battery is a device that stores chemical energy and converts it into electrical energy. The key idea here is that a battery is made up of two or more electrochemical cells connected together. When you link cells, their voltages add up, so the total electric potential increases as you add more cells. That’s why batteries are packs of several cells rather than just a single cell.

Think of a single cell as the basic unit that can produce electricity, while a battery combines multiple of these units to deliver higher voltage. If cells were connected in parallel rather than in series, you’d increase capacity more than voltage, but in the typical battery setup the goal is to raise the overall potential difference by having multiple cells. The other options describe a single cell, a device that converts kinetic energy to electricity, or a device that measures current, which don’t define a battery.