1.2.1 Ohm’s Law

German physicist Georg Ohm discovered Ohm’s law, which states that when the physical conditions of a conductor remain constant, the potential difference across the conductor is directly proportional to the current flowing through it.

When the current is represented by I and the potential difference by V, this relationship is expressed by the following equation.

It can also be expressed in the following forms.

If any two of the voltage, current, and resistance values in a circuit are known, the remaining value can be calculated.

1.2.2 Voltage Drop

When current flows through a conductor such as an electrical wire, some of the electrical energy is converted into heat due to the conductor’s electrical resistance. As a result, the voltage decreases from the power source toward the load.

This is called a voltage drop. According to Ohm’s law, the voltage drops by V = RI [V].

When tracing a complete loop around an electric circuit, the sum of all voltage drops is equal to the voltage applied to the circuit.

Figure 1.2-1 Voltage Drop

About This Article

Reference
・Fundamentals of Electricity, Volume I, Corona Publishing Co., Ltd., by Toshio Utsunomiya, Hiroshi Takahashi, and Isao Izumi
※This article was prepared with reference to the source listed above and organized based on the author’s understanding.