Inductor Transient Response Grade Name Date In each of the following, enter either a zero or a formula for the current. Inductors resist change in current. They store energy in the form of a magnetic field. Charging: When a voltage is applied, the inductor initially acts as an open circuit. After a long time, the inductor acts as a bare wire. R -O 47 ohms a) When the switch is closed to position A, the instantaneous current will be E -12 V 220 mH L b) After a long time, the current will be Discharging: When the voltage is cut off, the inductor acts initially to keep the current going in the same direction. c) When the switch is moved to position b, the instantaneous current will be d) After a long time at position b, the current will be Note that the voltage drop across the inductor is initially large, while the current is large at the end, so that the Emf for an inductor (L) leads the current I, giving the acronym ELI. Capacitors store energy in the form of electric fields. Their transient response is the opposite of inductors. Resistors are passive and respond immediately to any R changes with no transient response. Charging: the capacitor initially acts as a bare wire. After a long Vb time, the capacitor acts as an open circuit. e) When the switch is moved to a, the instantaneous current will be f) After a long time, the current will be Discharging: initially the capacitor drives a current the opposite way until it is drained to zero. g) When the switch is changed to position b, the instantaneous current will be h) After a long time, the current will be_ The current I through a Capacitor is initially large, but the capacitor voltage or Emf is large only after the capacitor is charged, so here the acronym is ICE. The delay in the current and/or voltage in reaching their final values is called a transient response. It is either an exponential decrease e / from a maximum value, or an exponential rise 1 - et/t to a maximum value. The time constant t (in seconds) is Tz = L/R for inductors or to = RC for capacitors