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the rate of flow of electric charge |
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direction of current (conventional) is the
direction positive charges would move (from positive to negative) |
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electromotive force |
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Not actually a force. A source of Emf will
convert mechanical, chemical or other sources of energy into electrical
energy. |
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Provides a continuous potential difference
across two points in a circuit |
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It is the energy or work (joules) supplied per
unit of charge (coulombs). Therefore it is measured in VOLTS |
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The opposition to the flow of electric charge.
It is measured in ohms (W). |
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The resistance of a material increases with
temperature. At very low temperatures resistance decreases to zero for some
materials called superconductors. |
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Resistance is NOT dependent on the Emf or the
current running through it. |
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The resistance of a wire depends on the length,
the cross-sectional area and the type of material. The property of the
material determining its resistance is called resistivity (r). |
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Resisitivity is constant only for a constant
temperature. Use Table 33-1(p.728) for resistivity at 20° C (room
temperature) |
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the current (I) in a conductor is directly
proportional to the applied voltage (V)and inversely proportional to the
resistance (R) of the conductor. |
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The energy gained in the source of Emf must
equal the energy lost in the circuit. The energy lost may be converted to
useful work or dissipated as heat. |
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Power loss - the rate of energy consumption or
heat loss in the electric circuit. |
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Notes