A wire of length L and 3 identical cells of negligible internal resistances are connected in series. Due to current, the temperature of the wire is raised by ΔT in time t. A number N of similar cells is now connected in series with a wire of the same material and cross-sectionbut of length 2L.The temperature of the wire is raised by the same amount ΔT in the same time t. The value of N is