Question

1- A moving coil instrument has a resistance of 2 ohms(Rm) and its reads upto 250Volts(full scale reading )when a resistance of 5000 ohms is connected in series with it. Find the current range of the instrument ( Im + Is) when it is used as an ammeter with the coil connected across a shunt resistance of 2 milli ohms(Rs).

2- - In the bridge shown below, the null detector is a 1 mA, 50 , 100 divisions galvanometer. The resistance R increases linearly with temperature, while the effect of temperature on the other resistances is negligible. (a) Determine the value of R that produces zero current in the galvanometer. (b) Calculate the current in the galvanometer if the temperature increased by 10%.

Answer 1