A galvanometer has an internal resistance of 100 Ω and deflects full-scale at 2.00 mA. What size resistor should be added to it to convert it to a milliammeter capable of reading up to 4.00 mA?
A)50.0 Ω in series
B)50.0 Ω in parallel
C)75.0 Ω in parallel
D)100 Ω in series
E)100 Ω in parallel

Question

Quizplus · Accepted Answer

To convert the galvanometer to a milliammeter that reads up to 4.00 mA, a shunt resistor is needed in parallel. The shunt resistor should allow 2.00 mA to pass through it when the total current is 4.00 mA. Using the formula for parallel resistors and the current division rule, the shunt resistor should be 100 Ω.

A Galvanometer Has an Internal Resistance of 100 Ω and Deflects