JEE Main201911 Jan 2019Evening ShiftPhysicsCurrent ElectricityActual
A galvanometer having a resistance of 20 and 30 division on both sides has figure of merit 0.005 ampere/ division. The resistance that should be connected in series such that it can be used as a voltmeter upto 15 volt, is:
Options
- A100
- B120
- C80
- D125
Correct answer
C. 80
Step-by-step solution
Deflection current = Ig _ =n x k=0.005 30 Where, n = Number of divisions =30 and k =0.005 amp / division array l =15 10⁻²=0.15 v = I _ g [20+ R ] 15=0.15[20+ R ] 100=20+ R R =80 array