Question

Rajiv connected two exactly similar heating elements (or resistances) across a mains supply in two different ways to heat some water.
(a) Is more heat obtained when the heating elements are connected in series or when they are connected in parallel?
​(b) Give reasons for your answer.

Answer 1

(a) More heat will be obtained when the heating elements are connected in parallel.

(b) Heat energy produced, H = I² R t

In the parallel combination of resistances, current increases due to a decrease in effective resistance.
As the heat energy produced is directly proportional to the square of the current, it can be concluded that the parallel combination gives more heat energy.