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Electric Charge. All matter is made up of very small particles called atoms. Atoms are made up of even smaller particles called protons, neutrons, and electrons . How are these particles that make up an atom different from one another?.
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All matter is made up of very small particles called atoms. • Atoms are made up of even smaller particles called protons, neutrons, and electrons. • How are these particles that make up an atom different from one another?
Protons and electrons are charged particles and neutrons are not. • Protons are positively charged particles • Electrons are negatively charged particles • Neutrons have no charge.
The law of electric charges states the like charges repel, or push away, and opposite charges attract. • Because protons and electrons have opposite charges, they are attracted to each other.
The Electric Force and Field • The force between charged objects is an electric force, which depends on two things: • the amount of charge on each object (The greater the charge is the greater the electric force is.) • the distance between the charges. (The closer the charges are the greater the force) • The electric field is the space around a charged object in which another charged object experiences an electric force.
Tape Experiment • What happens when a balloon is rubbed with a cloth and then brought near your hair? The balloon seems to have a type of energy that can make other objects move closer together or farther away. This is called a charge. Can pieces of tape show similar effects when brought together?
Make a prediction • If clear tape can hold a charge, then the pieces of tape will…
Test your prediction 1st - Press two pieces of clear tape tightly to your desk, folding over one side of each piece to make a small tab. 2nd- Pull the strips of tape off the desk by the tab end, and hold the other end of the tape close together. 3rd- Observe what happens and write what happens in a complete sentence in your output
Data from test 1 • In test one when I peeled the two pieces of tape off the desk, the two pieces of tape… • Explain Why.
Test 2 1st Tightly press two new strips of tape to your desk, but this time, stick one of the pieces on top of the other. 2nd Pull both strips off the desk at the same time. Then pull them apart. Hold the ends close together and observe what happens 3rd Record what happens in your output. Make sure you write in a complete sentence.
Results for Test 2 • In test two when I peeled the two piece stuck together off the desk and then peeled them apart, the two pieces of tape… • Explain Why.
Charge it! • Atoms have an equal number of protons and electrons. • This means that they have no charge because each proton cancels out each electron. • So how can anything made of atoms be charged?
Charge it! • Objects become positively charged when it loses electrons. • Objects become negatively charged when it gains electrons. • There are three ways to charge an object: • Friction • Conduction • Induction
Friction • Charging by friction happens when electrons are “wiped” from one neutral object to another neutral object. • If you use a cloth to rub a plastic ruler, elections move from the cloth to the ruler. The ruler gains electrons and becomes negatively charged. At the same time, the cloth loses electrons and becomes positively charged. • Two neutral objects are rubbed together and one object loses electrons (-) while the other object gains electrons (-).
Conduction • Charging by conduction happens when electrons move from one object to another by direct contact. • A neutral object is touched with a charged object (either positive or negative) and some of the charge moves onto the neutral object. Example: When a negatively charged plastic ruler touches an uncharged metal rod, the electrons in the ruler travel to the rod. The rod becomes negatively charged by conduction.
Induction • Charging by induction happens when charges in an uncharged metal object are rearranged without direct contact with the charged object. • A charged object is brought near but not touched to a neutral object. • If the charged object is negatively charged, it repels the negative charges in the neutral object. The object is still neutral, but there is now an excess of positive charges at one end and negative charges at the other.
Induction • http://phet.colorado.edu/sims/html/balloons-and-static-electricity/latest/balloons-and-static-electricity_en.html