Make elec tric c urre nt de fini tion, using concept of a n electrical c harg re R=rho (l)/(S) X=(omega C)^-1 I=(q)/(t) X=omega L U=IR I=(U)/(R)

electric current is the flow of electric charge. It is a fundamental concept in the field of electricity and magnetism. The definition of electric current can be derived from the concept of an electric charge.<br /><br />The formula for electric current is given by:<br /><br />$I=\frac {q}{t}$<br /><br />where:<br />- I is the electric current,<br />- q is the electric charge, and<br />- t is the time taken for the charge to flow.<br /><br />The unit of electric current is the ampere (A), which is defined as one coulomb of charge passing through a point in one second.<br /><br />The other formulas you provided are related to different concepts in electricity and magnetism:<br /><br />$R=\rho \frac {l}{S}$ is the formula for electrical resistance, where R is the resistance, ρ is the resistivity of the material, l is the length of the conductor, and S is the cross-sectional area.<br /><br />$X=(\omega C)^{-1}$ and $X=\omega L$ are formulas for the reactance of a circuit, where X is the reactance, ω is the angular frequency, C is the capacitance, and L is the inductance.<br /><br />$U=IR$ and $I=\frac {U}{R}$ are Ohm's law formulas, where U is the voltage, I is the current, and R is the resistance.