1.

Three ammeters — 1, 2 and 3 have different internal resistances r_(1), r_(2) and r_(3) respectively. Internal resistance r_(1) isknown but r_(2) and r_(3) are unknown. The angular deflection of pointer in each ammeter is proportional to the current. Initially, the three ammeters were connected in series to a voltage source (fig. a) and deflections for the three ammeters were theta_(1), theta_(2) and theta_(3) respectively. The three ammeters were then connected in parallel to the same voltage source (fig. b). This time the deflections were observed to be theta'_(1),theta'_(2) and theta'_(3) respectively. (a) Find r_(2) and r_(3). (b) If theta_(2) = theta_(3) but theta'_(3) gt theta'_(2) then which one is larger r_(2) or r_(3) ?

Answer»


ANSWER :(a) `r_(2)=r_(1)((theta_(2)theta'_(1))/(theta_(1)theta'_(2)));r_(3)r_(1)((theta_(3))/(theta_(1)).(theta'_(1))/(theta'_(3)))`
(b) `r_(2) GT r_(3)`


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