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## by River Valley Schools on Jan 14, 2010

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## CurrentPresentation Transcript

• Science 9, Bell Work, 12-16-2009
• ?
• ?
• How is electric charge measured?
• Electric charge like other types of energy begins as a form of potential energy.
• SI Unit = coulomb (C)
• How is electric charge measured?
• Electrical potential energy is the ability to move an electric charge from one point to another.
• Like gravitational potential energy, electrical potential energy depends on distance .
• It also depends on the type of charge .
• How is electric charge measured? High Elec. PE Low Elec. PE Lesser Distance Low Elec. PE High Elec. PE Greater Distance Attraction Repulsion
• What is potential difference ?
• A measurement of how much work must be done to move a charge from point A to point B.
• Potential difference is called voltage .
• SI Unit =Volt (V)
• Battery cells use potential difference to store and produce electric current.
• Positive and negative terminals.
• Current flows from negative to positive .
• What is electric current?
• Current is the rate that an electric charge flows through a conductor.
• SI Unit = ampere (A)
• Symbol = I
• 1 amp = 1 coulomb per second.
• Current that flows across terminals in one direction is called direct current .
• Batteries produce direct current.
• What is electrical resistance?
• The opposition to the flow of current through a material or device.
• Resistance is caused by internal friction of a conducting material on the electrical charge.
• Resistance = Voltage / Current
• R= V/I
• SI Unit = ohm(  )
• What is electrical resistance?
• Conductors  low resistance .
• When certain materials drop below a certain temperature they have zero resistance to electric current.
• Superconductors
• Used in electrical filters, powerful magnets and Maglev high-speed trains.
• What is electrical resistance?
• Semi-conductors  medium resistance
• Used in complex electrical devices like computer chips.
• Insulators  high resistance
• Insulate wires carrying current.
• “ Grounding” materials and objects.
• Providing a path for current to flow into the Earth.
•