Alternating Current

Inductive Reactance

  • If an a.c. voltage is applied to an inductor the reverse voltage (back emf) generated causes the current to lag the voltage by 90°
  • The ratio of voltage to current is the reactance (XL) measured on Ohms (Ω)
  •    XL = V ÷ I ;      I = V ÷ XL ;      V = I × XL
            [V, I are rms values]
  •    XL = 2πƒL   Reactance increases with frequency