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Electron has a _________ charge ______ has a no charge Proton has a ________ charge But what is a charge? Electric charge, like mass, is a _____________ ___________ of matter. Inside atoms found in matter, ____________ between positive and negative charges holds the atoms together. Virtually ______________around you has electric charge because atoms are made of electrons and protons (and neutrons). But.... ordinary matter has ____________________________, most matter acts as if there is no electric charge at all. _______ _______ _______ _______ Greater affinity for e- : stick to electrons more and _______________________becoming negative Less affinity for e- : don’t hold electrons as tight and are more ________________________ and become positive Charging by Friction A _________does not have much affinity for electrons. Becomes ____________ PVC becomes ____________ (Hold electrons tightly) Most likely to gain electrons and become negative (Hold electrons loosely) Most likely to lose electrons and become positive) PVC Rubber Cotton Paper Silk Fur Wool Nylon Hair Acetate Glass Material through which ______________________ Examples (gold, silver, copper, and aluminum) The general rule is that good thermo conductors are ___________________________ conductors Metals ____________________________ in electron clouds electrons are _____________________ around making them better conductors. Material through which _________________ freely move Examples: rubber, paper, plastic, air ______________________________ by producing a path to the ground Electrons move _______________ charged objects ____________ until the object is neutral Electrons move ________________ ______________________ charged objects The earth both ______________ __________________ electrons while remaining overall neutral Grounding wand for Van De Graaff generator Section 2: Charging Objects Three Ways of putting a charge on an object 1. 2. 3. 1. Charging by Friction Charging by rubbing objects that have different affinities for electrons together Induction (______________________ __________________) 1. 2. Bring a charged object (rod) _________ a neutral one (ball) without contact The electrons in the ball will be ____________ leaving a positive side - +- - + + - -+- + + + + + --- 3. The (now) _________________ball will be attracted to the negative rod Induction (charging without contact) Induction is only a ____________ change without contact therefore electrons are not transferred The charge induced is _______________ Take away the rod and a _______________ will return - +- -- +- -+-- ++ + - - -- - + + + - Conduction (__________________ __________________) Conduction is a more permanent change _______________; electrons are ________________ and then isolated. Charge conducted is the ______________ + + - + + - + + - - +- - -+-- -+-- - After conduction the ball and rod _________ each other The unit of charge is the ____________ (C). The name was chosen in honor of Charles Augustin de Coulomb (1736-1806), the French physicist who performed the first accurate measurements of the force between charges. Electric forces are incredibly strong. A millimeter cube of carbon the size of a pencil point contains about _________________ of positive and negative charge. 3 factors affecting the magnitude of the force between two charged objects: 1. ________________ on the objects 2. _________________ between objects 3. _______________separating objects When using this equation: A positive force (F) signifies ________________ ◦ Both charges (Qs) must be positive or both negative A negative force (F) signifies _______________ ◦ One charge (Q1 or Q2) must be positive and the other negative el Coulomb’s Law is similar to _________________________________ Similarities: ◦ They both are used to calculate a ____________________ ◦ Both forces have an _________________relationship to distance ◦ They are both __________________________ Differences: ◦ Force of gravity is always __________________ ◦ Electrostatic force _________________attractive or repulsive ◦ Gravities constant is very small since gravity is a ____________ force ◦ Fg relates force created by a _________________, Fel relates force created by _______________ el Both electric and gravitational forces are field forces because objects ______________________ to be subjected to the force. Field forces are sometimes called “forces at a ________________.” Magnetic forces work similarly. Electrical Fields Electrical Field (E): an ______________________ __________________ around a charged object. Variable E Unit: newton per coulomb (N/C) ______________from the positive and ____________the negative In the direction a positive charge would travel in the field Spacing of lines show _____________________ • Two formula’s: E: electrical field (N/C) F: force (N) Q: charge (C) k: constant (For air, k = 9.0 x 109 N·m2/C2) d: distance (m) All charge lies on the _______________ of a conductor Electrical field inside a conductor is _______ E = 0 inside conductor The metal outside the car gives the car a path to the ground Here is more proof of shielding _____________ occurs when the electric field around a conductor becomes so strong. The ___________________ helping the charge make a break for the ground. Arc- a rapid discharge producing _______, _________, and _________. Electrical forces • Lightning is caused by a giant buildup of _________________. • The cloud, air, and ground can act like a _______________. • All the accumulated ___________ __________ flow from the cloud to the ground, _______________ along the path (to as much as __________°C) so that it glows like a bright streak of light. Charges are separated in storm clouds; + top and – bottom Ground under the cloud becomes ____________ charged by _____________ V = millions of volts; causes arc discharge with tremendous ___________. Electric current is caused by __________________ _________________ . Electric current comes from the motion of ____________________. current A capacitor is a __________________ for electric charge. Capacitors can be connected in series or parallel in circuits, just like resistors. A capacitor can be _____________ by connecting it to a ______________ or any other source of _________. A capacitor can be ________________ by connecting it to any ________________________that allows current to flow. Electric current is similar in some ways to a current of ___________. Like electric current, water current can ____________ and do __________. A waterwheel turns when a current of water exerts a ____________ on it. An electric circuit is a _______________ through which electric _____________ travels. A good example of a circuit is the one found in an electric toaster. __________ in electric circuits are similar in some ways to _____________________that carry water. When drawing a _________________, ___________ are used to represent each part of the circuit. ________________ are quicker and easier to draw than realistic pictures of the components. A _____________ is an electrical device that _________________carried by electric current in a specific way. Any electrical device that uses energy can be shown with a ___________________. Draw the symbol used in diagrams for a Wire Battery Light Resistor Switch Current only flows when there is a __________ and unbroken path, or a ____________________. Flipping a switch to the “______” position creates an ________________by making a break in the wire. Electric current is measured in units called _____________________________for short. One amp is a flow of a certain quantity of _______________________________. The amount of electric _________________a circuit always equals the __________________ the circuit. Voltage is a measure of ____________________ ___________, just like height is a measure of gravitational potential energy. Voltage is measured in __________________. A voltage difference of 1 volt means 1 amp of current does _____________________________. A difference in voltage provides the energy that causes ___________________________. A useful meter is a _____________________, which can measure _________ or _________, and sometimes _____________. To measure voltage, the meter’s probes are touched to two places in a circuit or across a battery. A battery uses ___________ ______________to create the voltage difference. Three 1.5-volt batteries can be stacked to make a total voltage of __________ in a flashlight. A pump is like _________________ because it brings water from a position of low energy to high energy. If you want to measure current you must force the current to pass _______________________. Water meter measuring water flow Multimeters can measure two types of current: alternating current ________ and direct current _________ Circuit breakers and fuses are two kinds of devices that ________ ______________________________by making a break that stops the current. Resistance is the measure of how strongly an object ______________________ through it. The relationship between electric current and resistance can be compared with water flowing from the open end of a bottle. The total amount of resistance in a circuit ____________________________________ in the circuit for a given voltage. Electrical resistance is measured in units called ___________. This unit is abbreviated with the Greek letter _______________ The current in a circuit depends on voltage and resistance. Ohm’s law relates _______________________ _____________________ with one formula. If you know two of the three quantities, you can use Ohm’s law to find the third. Every electrical device is designed with a resistor that causes the right amount of current to flow when the device is connected to voltage. A The resistance of many electrical devices varies with ____________ and ________________. A light bulb’s _________ _________________when there is ________________ because the bulb gets hotter when more current passes through it.