(a) An electric iron consumes energy at a rate of 880 W when heating is at the maximum rate and 330 W when the heating is at the minimum. If the source voltage is 220 V, calculate the current and resistance in each case. (b) What is heating effect of electric current? (c) Find an expression for the amount of heat produced when a current passes through a resistor for some time.

The problem requires the application of the concepts of electric current, resistance, and heating effect of electric current. In part (a), we need to calculate the current and resistance in two different cases. We can use the formulas Power = Voltage x Current and Resistance = Voltage / Current to solve this part. In part (b), we need to explain the heating effect of electric current, which is the phenomenon of rise in temperature of a conductor when electric current flows through it. In part (c), we need to derive an expression for the amount of heat produced when a current passes through a resistor for some time. We can use the formula W = VQ = IRQ = I^2Rt = (V^2/R)t to solve this part.