Ch 20 2 Electric Current And Ohm’S Law

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Ch 20 2 Electric Current And Ohm’S Law

  1. 1. Electric Current and Ohm’s Law 20-2
  2. 2. Electric Current <ul><li>A continuous flow of electric charge. </li></ul><ul><li>Measured in amps (A) = 1 coulomb per second </li></ul><ul><li>Direct current (DC) when charge flows in one direction </li></ul><ul><li>Alternating current (AC) is a flow of electric charge that regularly reverses direction. </li></ul><ul><li>EX – home plugs and lights </li></ul>
  3. 3. Electrical Conductors and Insulators <ul><li>Conductors are materials through which charge can easily flow </li></ul><ul><ul><li>Metals and water </li></ul></ul><ul><li>Insulators are materials through which a charge cannot flow easily. </li></ul><ul><ul><li>Wood, plastic, rubber and air </li></ul></ul>
  4. 4. Resistance <ul><li>Opposition to the flow of charges in a material </li></ul><ul><li>Measured in ohm. </li></ul><ul><li>A material’s thickness, length, and temperature affect its resistance. </li></ul><ul><li>A thinner, longer and hotter wire increase resistance. </li></ul><ul><li>Superconductor has almost 0 resistance </li></ul>
  5. 5. Voltage <ul><li>In order for a charge to flow in a wire, the wire must be connected in a complete loop that includes an energy source. </li></ul><ul><li>Potential difference - difference in potential energy between 2 places in an electric field </li></ul><ul><li>Measured in volts – joules per coulomb </li></ul><ul><li>Batteries convert chemical energy into electrical energy. </li></ul>
  6. 6. Ohm’s Law <ul><li>Voltage (V), in a circuit equals the product of the current(I) and the resistance ( R). </li></ul><ul><li>V = I x R or I = V/R </li></ul><ul><li>Increasing voltage increases current. Keeping same voltage and increasing the resistance decreases the current </li></ul>

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