INTRODUCTION HOW COULD SCIENTISTS LIGHT UP A CITY It's September 4 1882 You're strolling through New York City when you notice a huge crowd on Pearl Street Suddenly at three o clock in the afternoon you see a flash For the first time ever roughly four hundred electric lamps are shining on Pearl Street Modern people depend on electricity to operate everything from televisions to trains Electricity is a form of energy We also rely on electricity to heat and cool buildings and of course to provide light Yet this wasn't always the case It took scientists a long time and a lot of testing to bring electricity to Pearl Street and beyond At first people didn't know what electricity was Still they noticed its effects on the world around them They mainly observed how a strange force caused certain objects to be attracted to each other Scientists asked themselves questions about this force After they finally identified it as electricity they had even more questions They wondered how electricity reacted with
Thomas Edison shows off a replica of the type of lamp used to light Pearl Street in 1882 other forces such as magnetism They also wanted to know if and how electricity could be used to do work Like detectives scientists searched for clues to investigate such mysteries During their investigations they conducted many exciting experiments These tests helped them collect data or information After reviewing their data scientists formed conclusions or answers to their questions Finally they shared what they had discovered This is called scientific inquiry It's what allowed US inventor Thomas Edison to light up Pearl Street in 1882 Like many scientists before and after him Edison changed the world by investigating electricity 5
CHAPTER 1 WHAT IS ELECTRICITY If you didn't have electricity how would you play video games or charge a cell phone You probably find it hard to imagine life without electricity But what exactly is electricity One way to answer this question is to think about what electricity does As energy it travels through wires and helps operate machines Scientists also explain electricity by describing what it's made from a flow of electrical charges A charge is a property of matter Electrical charges flow from an energy Source through wires to power devices machines and
7 Some charges are negative and others are positive Opposite charges attract Similar charges repel each other People noticed the effects of opposite electrical charges as early as 600 BCE The ancient Greeks were amazed by how feathers stuck to amber after they rubbed it with animal fur Rubbing this mineral gave it a negative electrical charge In turn the amber attracted objects with a positive charge The Greeks didn't know it but they were observing static electricity Static electricity is energy that builds up in one spot It's one of two main forms of electricity The other is current electricity That's energy that travels from place to place in a flow or current A CLOSER LOOK AT LIGHTNING Centuries later scientists were determined to understand electricity better They searched for clues in the world around them In the eighteenth century Benjamin Franklin wondered whether people could harness the energy lightning from
