Unit 4 The Characteristics of Electricity

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  1. Electricity
    Form of energy resulting from interaction of charged particles, like electrons or protons.
  2. Static Charge (Static Electricity)
    • An electric charge that tends to stay on the surface of an object, rather than flowing away quickly.
    • The charge is static.
    • Related: Static charges build up through charging by friction.
  3. Charging by Friction
    • Transfer of electric charge by rubbing or friction (different materials).
    • ex. rubbing a rubber balloon against a wool sweater.
    • Related: one material has a stronger hold on electrons , therefore pulling electrons away from the material with the weaker hols on electrons.
  4. Electrostatic Series
    • List of materials that have been arranged according to their ability to hold on to electrons.
    • Substances high in the list lose electrons, become positively charged.
    • Substances low on the list gain electrons and become negatively charged.
    • The closer the materials are on the list, the weaker the transfer of electrons.
  5. Insulator
    • Materials where electrons cannot move easily from one atom to another.
    • These materials have a strong hold on electrons.
    • All the materials on the electrostatic series were insulators.
    • ex: glass, rubber, wool, etc.
  6. Conductor
    • Material where electrons can move easily between atoms.
    • Usually metals.
    • ex: silver, copper, aluminum, gold, etc.
  7. Semiconductor
    • Material in which electrons can move fairly well between atoms.
    • Non-metals.
    • ex: silicon.
  8. Ground
    • Object which can supply a very large number of electrons to, or can remove a very large amount of electrons from, a charged object, neutralizing it.
    • Ground remains neutral.
    • Simplest way to remove a net charge on an object.
    • fc,550x550,white
  9. Electroscope
    • (simple) Device used to detect the presence of an electric charge.
    • ex: pith ball and metal leaf electroscopes.
    • Pith is an insulator, covered by a conducting substance. When a charged object comes close to the pith ball, there is an electric force between them. The small mass of the pith ball causes it to move.
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  10. Charging by Contact
    • Generating a charge on a neutral object by touching it with a charged object.
    • An object charged by contact always gets the same type of charge that is on the object that charges it.
    • ex: a negative rod charges a neutral pith ball with a negative charge.
    • a positive rod charges a neutral pith ball with a positive charge.
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  11. Laws of Electric Charges
    • Laws that describe how two objects interact electrically when one or both are charged.
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  12. Electric Field
    • Property of space around a charged object, where the effect of its charge can be felt by other objects.
    • The electric field of an object can cause induced change separation.
    • Related: The electric field of a charged object is weaker as an object is farther away from it.
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  13. Induced Charge Separation
    • Movement of electrons within a substance; it is caused by the electric field of a nearby object - NOT direct contact.
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  14. Ion
    • Charged atom or group of atoms.
    • Positively charged ions are what move in a lightning strike, not protons.
    • lightning_stroke
  15. Lightning Rod
    • Metal sphere or point, attached to the highest part of a building and connected to the ground.
    • 2000px-Lightning-rod-diagram.svg
    • Lightning rods are conductors.
  16. Electrostatic Precipitator
    • Type of cleaner which removes unwanted particles and liquid droplets from a flow of gas.
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    • Dust particles and liquid droplets become positively charged when they touch a wire with a strong positive charge. These +vely charged particles induce a negative charge on the collection plates. When they collide with the plates, they are neutralized and collected in large containers (hoppers).
    • Effective at reducing pollution from smoke stacks
  17. Van de Graaff Generator
    • Device that accumulates very large charges.
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    • Have been used in atom smashers
    • Can accelerate particles to very high speeds.
    • A motor drives a lower roller, causing charging by friction between the motor and the belt. At the top of the roller is a collecting comb, which is attracted to the inside of the metal sphere. The charged belt induces a redistribution of charges in the comb, and charges accumulate on the metal sphere.
  18. Radiation Dosimeter
    • Small device that detects and measures exposure to radiation.
    • ex: some resemble a metal leaf electroscope, surrounded by gas. Gas usually does not conduct electricity, but radiation knocks electrons from the gas, causing it to become a conductor, and the metal leaves to lose electrons and come together.
  19. CHAPTER 2
  20. Electric Circuit
    Close path in which electrons powered by an energy source can flow.
  21. Voltaic Cell
    • Source of energy which generates an electric current by chemical reactions.
    • Involve different metals separated by a substance that is a conductor.
  22. Battery
    A connection of two or more cells.
  23. Electrode
    One of the two metal terminals in a cell or battery.
  24. Electrolyte
    Solution or paste that conducts charge.
  25. Dry Cell
    Cell that contains an electrolyte that is a paste.
  26. Wet Cell
    Cell that contains a liquid electrolyte.
  27. Primary Cell
    Cell that can be used only once.
  28. Secondary Cell
    Cell that can be recharged.
  29. Fuel Cell
    Cell that makes electricity through the chemical reactions of fuel that is stored outside the cell.
  30. Solar Cell
    Cell that converts sunlight into electrical energy.
  31. Terminal
    Location on a cell that must be connected to other components to make a circuit.
  32. Switch
    Device which can complete or break a circuit.
  33. Open Circuit
    Circuit that contains a gap or break.
  34. Electric Current
    • Rate of movement in an electric charge. (how many particles - electrons - move per time - second)
    • This is the variable.
  35. Coulomb (C)
    Quantity of charge; chart?chf=bg,s,00000000&cht=tx&chl=6.25%5Ctimes10%5E1%5E8&chs=146x36 electrons per coulomb.
  36. Ampere (A)
    Unit of electric current, equivalent to one coulomb per second.
  37. Electrical Resistance
    Property of a substance, which hinders electric current and and converts electrical energy into other forms of energy.
  38. Resistor
    Device used to decrease the current going through a component by a specific amount.
  39. Load
    Device (usually resistor) that converts electrical energy into other forms of energy, like sound, light, heat, motion.
  40. Potential Difference (voltage)
    • Difference between electric potential energy (energy that can do work) per charge (unit is coulomb) at two points in a circuit.
    • Potential difference = difference in potential energy (J) / charge (C)
  41. Volt
    Unit for potential difference, equivalent to one joule per coulomb.
  42. Circuit Diagram
    Diagram which uses standard symbols to represent an electric circuit.
  43. Series Circuit
    Circuit in which there is only one path which electrons can flow.
  44. Parallel Circuit
    Circuit in which there is more than one path electrons can flow.
  45. Ohm's Law
    • Potential difference : Current
    • R=V/I
    • V=IR
  46. Ohm (Ω)
    Unit for resistance, equal to one V per Amp (V/A)
  47. Superconductor
    Material through which electric charge  can flow with no resistace
  48. Non-ohmic
    Not following ohms Law.
  49. Loads in Series
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  50. Loads in Prallel
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    The resistance of the loads that are connected in parallel is less than the resistance of the smallest load
Card Set
Unit 4 The Characteristics of Electricity
Glossary Terms.
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