Using Ohms

The effects of different voltages and different resistances on current flow can be seen in the sample circuits. Current found by dividing voltage by resistance. This can be very helpful when diagnosing electrical problems:

• When the resistance stays the same ... current goes up as voltage goes up, and current goes down as voltage goes down. A discharged battery has low voltage which reduces current. Some devices may fail to operate (slow motor speed). An unregulated alternator may produce too much voltage which increases current. Some devices may fail early (burned-out lamps).

• When the voltage stays the same ... current goes up as resistance goes down, and current goes down as resistance goes up. Bypassed devices reduce resistance, causing high current. Loose connections increase resistance, causing low current.

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