Sensitivity of the ammeter means that how small a current the ammeter can measure. Example, if the original set up is 0.2 A per division, and the modified set up can measure up to 0.1 A per division, so we say the latter one is more sensitive as it is able to measure smaller change in the currrent.

Based on individual calculations, the highest effective resistance will only be achieved if the junctions are connected at Q and S.

Solutions: Option B Whatever that goes in has to come out. With this basic concept, you will be able to solve this question easily. Ignoring the unknown branch, Total current going into O = 8A + 6A = 14A Total current going out of O = 12A + 4A = 16A Hence in order to be equal, 2A must be flowing in direction PO. Hence answer is B.

The concepts needed to solve such questions Length increases, resistance increases and vice versa. Finding resistors in parallel and in series.