a galvanometer having 30 divisions has a current sensitivity of 20 micro ampere and resistance 25ohm. how will you convert it to measure current of 1 ampere??

Question

radar · Answer

From the info you've provided, I believe you are saying the meter reads full scale at 20 micro ampere and has an internal resistance of 25 Ohms.  You desire to use this meter to measure 1 ampere.

For this to read full scale at 1 ampere (which is one million micro ampere) you will need to shunt 999,980 micro amps around the meter with the remaining 20 micro amps passing thru the meter.  This means you must calculate the value of this shunt resistor.|dw:1410226348148:dw|