Question

In the given circuit diagram, the cell and the ammeter, both have negligible resistance. The resistances are identical. With the switch K open, the ammeter reads 0.6 A. What will be the ammeter reading when the switch is closed?

Answer 1

Let the value of each resistance be 'R'.
(i) When key'K' is open the only two resistance are in a circuit so resultant resistance, in this case, is the parallel combination of two resistances.

(ii) Now, when key 'k' is closed, all three resistances are parallel in the circuit. Therefore,