Q23 of 126 Page 198

If the reading of ammeter A1 in figure is 2.4A, what will the ammeters A2 and A3 read? Neglect the resistances of the ammeters.


1.6A, 4A

Given,


Current through A1 ammeter, i-i1= 2.4A


Formula used:


Depending on the resistance offered by each paths of a circuit, the current split inversely. The voltage across the two branches will be same as they are connected parallel.



Solution:


The current going through Ammeter A3 will split into two. To find the current in two branches, let’s equate the voltage in each branches.


Hence,



By substituting the value of i-i1= 2.4A, we get i1 that goes through ammeter A2 as,



Hence the total current i, passing through A3



Hence the current through A2 and A3 are 1.6A and 4A.


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(a) Find the current in the external resistance.


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Three bulbs, each having a resistance of 180 Ω, are connected in parallel to an ideal battery of emf 60 V. Find the current delivered by the battery when

(a) all the bulbs are switched on,


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