Question

When a steel-cored reactor and a non-reactive resistor
are connected in series to a 150 V a.c. supply, a current
of 3.75 A flows in the circuit. The potential differences
across the reactor and across the resistor are then
observed to be 120 V and 60 V respectively. If the d.c.
resistance of the reactor is 4.5 Ω, determine the core
loss in the reactor and calculate its equivalent series
resistance.