In the circuit shown in the figure, we have to find the current flowing through the ammeter A, assuming that A has zero resistance.

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It is a multi-loop circuit. We have indicated currents in different branches of the circuit by taking care of conservation of charge. We have three unknown currents, and , as .

Considering the circuit abcde and applying Kirchoff’s law, we get

Applying Kirchoff’s law to loops bfgc and cghd, we get

We now have three linear equations connecting , and . We solve them and find

Therefore, the current in the ammeter, , will be