An electric iron is labelled "500W,220V" and is used on a domestic supply that sometimes drops to 200V.
(i) Calculate the resistance of the heating element when it operates at its rated values.
(ii) Find the quantity of heat produced by the iron in 15min when the supply voltage is 220V.
(iii) Determine the power consumed and the heat produced in the same time interval when the supply voltage falls to 200V, assuming the resistance remains unchanged.
(iv) Explain how the fall in supply voltage affects the performance of the iron in everyday use.