| Alternating Current Circuit Calculations |
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| Impedance: |
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| In A.C. circuits the current is limited by the impedance (Z). Impedance is measured in ohms, and |
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| volatage = current (amperes) X impedance (ohms) |
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| U = I x Z |
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| Inductive Reactance: |
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| In alternating current circuits which set up significatant magnetic fields, there is opposition to the current in addition to that caused by the resistance of the wires. This in additional opposition is called inductive reactance. |
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| Inductive reactance |
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| Capacitive Reactance: |
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| When a capacitor is connected to an A.C. supply, the current is limited by the reactance of the capacitor (Xc) |
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| Impedance in Series Circuit |
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| Impedance is the name given to the combined effect of resistance (R) and reactance (XL or XC). It is measured in ohms. |
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| For series circuit, impedance (Z) is given by: |
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| Where |
X = XL for a resistive inductive circuit |
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X = XC for a resistive capacitive circuit |
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| And |
X = XC - XL or XL - XC (the larger minus the smaller for a circuit with resistance, capacitance and inductance) |
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