A capacitor made of two circular plates each of radius 12 cm and separated by 5mm. The capacitor is being charged by an external source. The charging current is constant and equal to 0.15A. The magnetic field between the plates at a point 15 cm from the axis is

Consider a loop of radius ’r’ between the two circular plates placed coaxially with them . Area of the loop  A'=πr2In this case, only displacement current ID will cross the loop. Therefore using Ampere’s Maxwell law, we have∮B→.dl→=μoID ⇒2πrB=μox( current passing through the area A')  ⇒2πrB=μoI×πr2πR2     [for rR  ,   B=μ0I2πr∴  B=4π×10−7×0.152π×0.15=2×10−7T