Total resistance $=\frac{1}{5} \times \frac{R}{5}=\frac{R}{25}$
Reason : Dimness decreases after sometime.
Reason : Resistance of wire is proportional ot resistivity of material.

$(i)$ The equivalent e.m.f. is smaller than either of the two $e.m.f.$ is
$(ii)$ The equivalent internal resistance is smaller than either of the two internal resistances


Reason : Glow (Power) which is directly proportional to square of current.