A cell supplies a current of 0.6A through a 2 Ohms coil and a current of 0.2A through a 7 Ohms coil. Calculate the e.m.f. of the cell.
Answers
Answered by
2
Answer:
1.5 V
Explanation:
Let the cell resistance be r.
For the first circuit we analyze it as follows :
The internal resistance of the cell. is constant.
Current = 0.6 A
R = 2 Ohms
V(emf) = I(Total resistance)
Total resistance = r + 2
V(emf) = 0.6(r + 2)
= 0.6r + 1.2
The second circuit:
Current = 0.2 A
Resistance = 7 ohms
V(emf) = 0.2(r + 7) = 0.2r + 1.4
We equate the two as follows :
0.2r + 1.4 = 0.6r + 1.2
1.4 - 1.2 = 0.6r - 0.2r
0.2 = 0.4r
r = 0.2/0.4 = 0.5
Substituting this we have :
0.6(0.5 + 2) = 2.5 × 0.6 = 1.5 V
The emf of the cell is 1.5 V.
Similar questions