Unit 3 The Characteristics of Electricity ( pg 296 )
Electrostatics - study of static electricity
Neutral objects - materials that do not carry a charge
Conductors allow charges (electrons) to flow through them easily. E.g. metal Therefore no matter how hard that you rub a metal tap no static charge will build up because the electrons that you are giving the tap just keep on moving up the tap and down the water line until they reach a ground. Insulators do not allow charges to flow through them. The charge builds up on its surface eg. Faraday Cage Both a positive and a negative charge can build up on ____________________ Only ______________ can obtain a static charge.
Conductors, Insulators and in – between (pg 308)
Conductivity is the ability of materials to allow electrons to move freely in them. Materials that hold onto their electrons and do not allow them to move easily are called electrical insulators.An electrical insulator is a solid, liquid, or gas that resists or blocks the movement of electrons. Dry wood, glass, and plastic are all examples of electrical insulators. An insulator can hold a static charge because static charges remain nearly fixed in place.
Since electrons cannot move through an insulator they can be very useful to us to protect us from shocks. For example a simple electric kettle would be very hazardous if the two wires that supplied electricity to it did not have a rubber coating over them See Table pg 308 for some common insulators and conductors. metals are good conductors since e’s can jump from one atom to the next rubber and plastics are insulators since they hold their e’s tightly Why do you get more shocks in the winter than in the summer?
This is because in winter the air is far dryer than in the summer and dry air is an insulator and therefore does not take any of the charges our body might pick up during the day. So when we go and touch another conductor (a door handle) ZAP we receive a shock. The Electrical Nature of Matter pg 301
electric charge- can be positive or negative
neutral - they have an even number of positives and negatives INCLUDEPICTURE "_themes/radius/aradbul1.gif" \* MERGEFORMATINET an object has a negative charge if it has more negatives than positives INCLUDEPICTURE "_themes/radius/aradbul1.gif" \* MERGEFORMATINET an object has a positive charge it it has fewer negatives than positives The Law of Electric Charges- like charges repel one another, unlike charges attract one another, charged objects are attracted to uncharged objects A Model for the Electrical Nature of Matter : The atom is composed of electric charges. Protons – positive charge, found in nucleus, cannot move Neutrons- neutral charge, found in nucleus, cannot move
Electrons- negative charge, found orbiting nucleus, can move from atom to atom A model for the electrical nature of matter.
All matter is made up of submicroscopic particles called atoms At the center of each atom is a nucleus, with two kinds of particles: the positively charged protons and the uncharged neutrons. Protons do not move from the nucleus when an atom becomes charged A cloud of negatively charged particles called electrons surround the nucleus. An electron has the same amount of charge as a proton, but the kind of charge is negative. When atoms become charged, only the electrons move from atom to atom. Like charges repel each other; Unlike charges attract each other. In some elements, such as copper, the nucleus has a weaker attraction for its electron than in others, and electrons are able to move freely from atom to atom. In other elements, such as sulfur, the electrons are strongly bound to each atom. In each atom, the number of electrons surrounding the nucleus equals the number of protons in the nucleus. A single atom is always electrically neutral. If an atom gains an extra electron, the net charge on the atom is 1- ,...
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