Electrical resistance is a physical quantity that characterizes a conductor's ability to impede the movement of electric charges. For direct current (DC), the resistance of a conductor is calculated by the formula:
$$R=\rho \cdot \frac{l}{A}$$
where,
lβ length of the conductor in meters;
Aβ cross-sectional area of the conductor in square meters;
qβ specific resistance of the material in ohm-meters.
In a direct current circuit without an electromotive force source, the resistance \(R\) is equal to the ratio of the applied voltage \(U\) to the current \(I\) flowing through the circuit:
$$R=\frac{U}{I}$$
where,
Uβ applied voltage to the electric circuit;
Iβ current intensity flowing through the circuit.
Unit of resistance in the International System of Units (SI) is the ohm (Ω). The resistance of a part of an electric circuit is 1 ohm when a voltage of one volt (1V) across the ends of the circuit produces a current intensity of one ampere (1A) in that circuit segment.
Electrical Resistance FAQ
What is electrical resistance?
It is the opposition a conductor offers to electric current.
What are the formulas?
R = Οl/A and R = U/I.
