Ohm's Law defines the relationship between voltage (V), current (I), power (P) and resistance (R) in electrical circuits. It was discovered in 1827 by Georg Ohm (1789 – 1854), a German mathematician and physicist who, as a high school teacher, decided to study Alessandro Volta's new invention: the electromechanical cell (the precursor of the battery).
The relationships between the four important parameters of circuits are as follows:
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Voltage (V, in volts) calculations:
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Current (I, in amps) calculations:
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Power (P, in watts) calculations:
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Resistance (R, in Ω) calculations:
To use this calculator, enter a value for any two of the following: voltage, current, resistance, and power.
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Decade boxes and dividers provide highly accurate and digitally variable standard values of resistance, capacitance, inductance, voltage and/or current for calibration, comparison and testing.
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Current sensing resistors convert the current flowing through it to a voltage drop. Monitoring or measuring this voltage drop allows the current through the resistor to be measured. Applications for current sensing resistors include power supplies, receptacles, and battery packs.
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Dynamic braking resistors (DBRs) produce braking torque and absorb the high amounts of energy generated by stopping electric motors. They are used in variable-speed drive systems such as elevators, cranes, and trains.
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Resistors are electrical components that oppose the flow of either direct or alternating current. They are used to protect, operate, or control circuits.
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