^Current in LR – circuit
An ideal inductor has no ohmic resistance (i.e. R = 0) it has only reactance (i.e. XL ≠ 0). However no inductor is ideal, every inductor can be assumed as series combination of L & R . When such an inductor is connected is connected to a battery (e.g. on throwing switch towards) a current increases exponentially in the outer loop from 0 to become maximum in accordance with the relation
Due to increase in current voltage across the resistor increases in accordance with the relation
As the total voltage across the LR combination is always fixed & equal to battery voltage, thus the increase in voltage across the resistor implies a decrease in voltage across the inductor. This is described by the function .
On throwing switch towards B current decreases exponentially in the outer loop from maximum to become 0 in accordance with the relation