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Ohm's law

Ohm's law (ōm) [for G. S. Ohm], law stating that the electric current i flowing through a given resistance r is equal to the applied voltage v divided by the resistance, or i=v/r. For general application to alternating-current circuits where inductances and capacitances as well as resistances may be present, the law must be amended to i=v/z, where z is impedance. There are conductors in which the current that flows is not proportional to the applied voltage. These do not follow this law and are called nonohmic conductors.

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Ohms law

Ohm's law Statement that the amount of steady current through a material is proportional to the voltage across the material. For example, if the voltage doubles then the current also doubles. Proposed in 1827 by the German physicist Georg Ohm (1787–1854), Ohm's law is expressed mathematically as V = IR (where V is the voltage in volts, I is the current in amperes, and R is the resistance in ohms).

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Ohms law

Ohm's law The ratio of the voltage (V) applied to a conductor and the electric current (I) caused to flow through it at constant temperature is constant, and is the electrical resistance (R) of the conductor, such that V/I = R. At high current densities the law may break down for some materials.

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Ohm's Law

Ohm's law

Ohm's law is a relationship between the voltage across an electric circuit , the electrical resistance in the circuit, and the current in the circuit. This law is named after its discoverer, Georg Simon Ohm. Ohm found that for most electric circuits, the voltage across the circuit was equal to the current flowing through the circuit times the electrical resistance of the circuit. For the same voltage, a circuit with a low resistance will have a higher current than a circuit with a higher resistance. The voltage, properly called the potential difference, is measured in volts, and the current in amperes (amps). The resistance is therefore in volts per ampere, which is defined as ohms.

It is important to understand that Ohm's law is not a fundamental law that always applies, such as the law of gravity. Rather it is an empirical law that has been found by experiment to work fairly well most of the time. There are times, however, usually in extreme cases, when Ohm's law breaks down. For example, if an extremely high voltage is applied across a circuit, Ohm's law will not predict the correct value for the current. Even though Ohm's law does not always apply it works for most everyday situations and is therefore very useful.

For example, why will a short circuit blow a fuse or circuit breaker? When a short circuit occurs, most of the electrical resistance in the circuit is bypassed. In effect, a new circuit with a very low resistance is created. So, according to Ohm's law if the resistance is very low the current must be very high. Fuses and circuit breakers are designed to protect the circuit by blowing when the current becomes too high. Hence, the short circuit will produce a current high enough to blow the fuse. As another application, electronic devices often have resistors placed in the circuit to increase the resistance and therefore limit the current.

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