# Electricity

#### Question 4:

Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be −

(a) 1:2

(b) 2:1

(c) 1:4

(d) 4:1

#### Answer:

(c) The Joule heating
is given by, *H = i*^{2}*Rt*

Let, *R* be the
resistance of the two wires.

The equivalent
resistance of the series connection is *R*_{S}*
= R + R = 2R*

If V is the applied potential difference, then it is the voltage across the equivalent resistance.

The heat dâ€¦

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