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Academic 1 2 3 4
History of Electricity Notes
Timeline:
Early B.C. Magnetism was studied but how to harness it was unknown.
1269- Petrus Peregrinus de Maricourt, a French scientist published research on magnets.
1600- Gilbert published book called “Of Magnets, Magnetic Bodies, and the Great Magnet of Earth.” Discovered that earth behaves like a huge magnet.
1745- The Leyden Jar was invented by Musschenbroek. What was it? A glass vial that contained water and a conducting wire capable of storing a static charge. Ben Franklin’s kite was connected to a string that was connected to a Leyden Jar. This experiment proved that lightning was an electrical discharge. (Benny never held the kite, he would have been killed)
1820- Hans Oersted (Dutch) showed that current would deflect a compass needle. This proved that there was a link between electricity and magnetism.
Later that year, Andre Ampere (French) established the laws of magnetic force between electric currents.
Michael Faraday took (English) took this information and discovered that moving a magnet near a wire induced current. (this is how electricity is made today)
Maxwell- Translated these findings into math.
1886- Heinrich Hertz (German) verified the existence of electromagnetic waves when he discovered radio waves.
-note- None of these discoveries would have been made if work had not been done previously. This illustrates the importance of scientists sharing information.
The history of magnetism and electricity is an illustration of how science often is the result of the investigations of many people over centuries.
Scientists do not work alone in any field. Documentation is very important. The advancements in electricity would have been much slower if each scientist has to rediscover the findings of the scientists before them.
Chapter 1: Section 1.
Objectives:
-Describe how objects can become electrically charged
-Explain how electric charges affect other charges
-Distinguish between insulators and conductors
-Describe how electric discharges such as lightning occur.
- We must return to atoms for a bit, everything is made up of atoms. Atoms are made up of 3 particles: Protons, electrons, and neutrons. Remember that protons and electrons are the only charged particles. Neutrons are neutral.
- The two types of electric charge are positive (protons) and negative (electrons).
- The amount of negative charge is equal to the amount of positive charge in neutral atom.
- When an atom loses or gains an electron it becomes an ion.
- Remember that electrons can move from atom to atom and from object to object. Rubbing a balloon transfers electrons from your hair to the balloon. As your hair loses electrons and the balloon gains electrons they become attracted to each other.
- The buildup of electric charge on an object is called static charge.
- Flow of charge can be caused by the movement of ions in solution not just the flow of electrons. When NaCl is dissolved in water is makes Na+ ion and Cl- ion. Because of the positive and negative charges the charged signals can move.
- In an atom, when electrons are attracted to protons in the nucleus it creates an electric force. All charged particles exert an electric force on each other.
- Unlike charges attract. Like charges repel. “Like repels like.”
- Electric force is repulsive or attractive. More distance between charges = less force
- Charged objects don’t have to touch to exert a force on each other.
- An insulator is a material in which electrons cannot move through. Ex. Wood, glass, rubber, plastic.
- A conductor moves electrons easily. Electrons will spread out evenly over a conductor.
- The best conductors are metals. When metal atoms bond some of their electrons aren’t held tightly. These electrons can leave the atom creating metal ions. .
- What is a wire? Metal with an insulator over it. The electrons spread out in the metal carrying current from one place to another. The plastic prevents it from escaping.
- Electric discharge is the rapid movement of excess charge from one place to another. When you walk across a rug and are shocked by a door knob. You are discharging the charge that was build up on your body.
- What is grounding? Remember that electricity is lazy, it wants to take the quickest and easiest route to the ground. If lightning strikes your house it can ruin your appliances if they aren’t protected. Some houses are equipped with lightning rods. This is a metal rod that is placed as the highest point on your house. A wire is extended to the ground so that the lightning will hit the rod and safely go to the ground. This avoids hurting your electronics in your house.
Questions:
1) If two charges repel each other what can you assume about them?
2) What is the difference between an insulator and a conductor? List three of each.
3) Where have you experienced an electrical discharge before? Give two examples.
Welcome back from Turkey Break. It is full speed ahead for the rest of this year. We will finish electricity and magnetism before you leave for your holiday break.
