word problem

Asked by mahesh joshi | 16th Jan, 2012, 10:14: PM

Expert Answer:

Let us consider V as emf of the cell and r be the internal resistance
according to the statement : A cell supplies a current of 2 Amp when it is connected to a 5 ohms resistance
V/(5+r) = 2
this equation can be rewritten as
V = 10 +2r       ----(i)
according to the statement : A cell supplies a current of 1.2 Amp if it is connected to resistence 9 ohms
then the equation becomes
V/(9+r) = 1.2
this can be rewritten as
V = 10.8 + 1.2r     -----(ii)
solving (i) and (ii) we get
r = 1 ohms
and V = 12Volts

Answered by  | 16th Jan, 2012, 10:24: PM

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