Atsparumo

Atsparumo, also known as resistance, is a property of electrical conductors and components that opposes the flow of electric current. In circuit theory it is quantified by the resistance R, measured in ohms (Ω). According to Ohm's law, V = IR, where V is voltage and I is current; rearranged, R = V/I.

An object's resistance depends on material, temperature, length, and cross-sectional area. For a uniform conductor, R = ρ L / A, where ρ is the material's resistivity (an intrinsic property). Longer wires have higher resistance; thicker cross sections reduce it. Temperature changes alter resistivity, typically described by the temperature coefficient α: R(T) = R0 [1 + α (T − T0)]. Metals usually exhibit positive α.

In alternating current (AC) circuits, the resistance is part of the broader impedance Z, which also includes reactance X from inductors and capacitors. At a given frequency, Z = R + jX, and the magnitude |Z| determines current flow.

Measurement methods include direct DC tests with a voltmeter and ammeter, or precision four-point probes for resistivity; careful contact quality and temperature control are essential for accuracy.

Applications span electronics design, power transmission, and sensor technologies. Materials with low resistivity, like copper, provide low resistance paths; high-resistivity materials are used as insulators. Understanding atsparumo helps predict energy losses, heat generation, and circuit performance.