Batteries

Introduction

A battery is an electric storage device. Batteries come in many shapes, sizes, and voltages. No matter what their shape, however, all batteries have two terminals—positive and negative. Some batteries have both terminals on one end. AAA, AA, C, and D batteries, however, are built with the terminals at opposite ends. The positive terminal is on the end with the bump; the negative terminal is on the flat end. Inside the battery, a chemical reaction produces electrons that collect on the negative terminal.

Placing a wire between the two terminals causes a stream of electrons, called current, to flow. Voltage is a measure of the energy difference between two points in a circuit. Current and voltage can be difficult concepts to understand so some people compare them to water pipes. Current relates to the amount of water flowing in a pipe, while voltage relates to the water pressure. New household batteries have voltage values ranging from 1.5 to 9 volts; but after repeated use, the voltage decreases to the point where they are no longer able to supply enough current. In many battery-operated devices, such as calculators and digital cameras, you do not use just one battery. You group them together to form higher voltages. In Part I of this activity, you will learn to identify the different parts of a battery and you will investigate the different ways a Voltage Probe can be positioned. In Part II, you will use a Voltage Probe to measure the voltages of several different sizes of batteries. In Part III, you will measure the voltages of batteries as they are stacked together.

Objectives

In this experiment, you will

• Use a Differential Voltage Probe and NXT to measure battery voltage.
• Make observations about the size of different batteries.
• Measure the voltages of batteries as they are stacked together.