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The circuit shown in the figure contains three resistors R 1 = 100 Ω , R 2 = 50 Ω and R 3 = 20 Ω and cells of E.M.F.s E 1 = 2 V and E 2 . The ammeter indicates a current of 50 mA . Find the E.M.F (in V ) of the second cell. (The internal resistance of the ammeter and of the cell should be neglected)

Correct answer

4

Step-by-step solution

Using KVL : 1 0 0 i + 0.05 + 5 0 i - 2 = 0 1 5 0 i + 3 = 0 i = - 3 1 5 0 = - 0.02 A = - 2 0 mA So, the direction of i is opposite to what we have assumed. If we redraw the circuit. Using KVL : 2 0 × 0.05 + 1 0 0 × 0.03 - V 2 = 0 1 + 3 - V 2 = 0 V 2 = 4 V

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