A network of four unequal resistor `R_(1),R_(2),R_(3)` and `R_(4)` are connected in a network (see diagram) that contains a source of e.m.f E and an ammeter A. The source has negligible internal resistance. For this network,

Options

A. If `R_(3)gtR_(4)` the current in the resistor `R_(3)` will be less than that shown by the ammeter
B. if `R_(3)ltR_(4)` the current in the resistor `R_(2)` will be greater than that shown by the ammeter
C. if the source of e.m.f and the ammeter were physically interchanged in the network the ammeter will show the same current.
D. If the resistors `R_(2)` and `R_(1)` were physically interchanged, the ammeter will show the same current.

Answer

A, B, C, D

Explanation

(A) is corrent because the ratio of currents `i_(3)` and `i_(4)=A`, given by `(i_(3))/(i_(4))=(i_(3))/(A)=(R_(4))/(R_(3))`
if `R_(3)gtR_(4),i_(3)ltA`
(B). Is correct irrespective of `R_(3)gtR_(4)` or `R_(3)leR_(4)`
as the current in `R_(2)` is the main current. (c) follows from the [principle of reciprocity of EMF (source without internal resistance ) and current. (D). Interchanging `R_(1)` and `R_(2)` does not change the main current and hence current in ammeter