A voltmeter coil possesses a resistance of 50.0 and is connected in series with a 1.15 k resistor. It is capable of reading potential differences up to 12 V . If the identical coil is utilized to build an ammeter that can measure currents up to 2.0 A , determine the required resistance of the shunt.

Step-by-step solution

Let R_g be the resistance of the coil and R_s be the series resistance. R_g = 50.0 R_s = 1.15 k = 1150 The maximum potential difference is V = 12 V . The full-scale deflection current I_g is given by: I_g = V R_g + R_s = 12 50 + 1150 = 12 1200 = 0.01 A To convert this coil into an ammeter of range I = 2.0 A , a shunt resistance S is connected in parallel. S = I_g R_g I - I_g Substituting the values: S = 0.01 50.0 2.0 - 0.01 = 0.5 1.99 0.251