Current, Ohm’s Law, Etc. The Continuity Equation for Steady State Currents Currents and current...
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Transcript of Current, Ohm’s Law, Etc. The Continuity Equation for Steady State Currents Currents and current...
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Current, Ohm’s Law, Etc.
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The Continuity Equation for Steady State Currents
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Currents and current densities are constant in time – steady state. The flux of out of any closed surface must be zero.
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Drift velocity
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For steady state situation
1.Kirchhoff’s junction rule: The algebraic sum of the currents into any junction is zero.
2.Kirchhoff’s loop rule: The algebraic sum of the potential differences in any loop must be zero.
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Resistors in parallel:
Resistors in series:
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Circuit with capacitors
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Joule’s Law
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Why does a light bulb burn out when you switch the light on and never when you turn it off?
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The amount of current drawn by a given device is determined by its power inputi
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A kitchen circuit
An 1800-W toaster, a 1.3-kW electric frying pan, and a 100-W lamp are plugged into the same 20-A, 120-V circuit.
a) What current is drawn by each device, and what is the resistance of each device?
b) Will this combination blow the fuse?
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To prevent the fuse from blowing, you replace the fuse with one rated at 40 A.Is this a reasonable thing to do?
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Wheatstone bridge
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British scientist and inventor1802-1875
Charles Wheatstone
Samuel Hunter Christie, British scientist and mathematician
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Wheatstone English concertina
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Electromotive force