Calculate the value of resistance needed to convert a galvanometer
Answers
According to me question is incomplete, so i am going to solve this question by adding some values, you can change that by analyzing your requirements.
Here the full question is: What is the value of resistance needed to convert a galvanometer of resistance of 200 ohms which gives a full-scale deflection for a current of 5 mA into a voltmeter of 0 to 25 V range?
Answer: To determine 25V max, put resistance in series along with galvanometer by allowing 5mA of current flowing through the galvanometer at 25 Volts. The total resistance can be calculated as :
rtotal = Vmax/Imax
rtotal = 25V/5mA
rtotal = 5k ohm
In total galvanometer contains 200 ohm resistance, to get the additional resistance remove 200 ohm from the total resistance. So the value of the additional resistance should be 4800 ohm, which is connected in series with the galvanometer.