JAMB Physics 2010 Paper

Concept:A galvanometer is converted into a voltmeter by connecting a large resistance in series so that the total voltage at full-scale deflection equals the desired voltmeter reading.Explanation:Let the galvanometer resistance be $G$.Full-scale galvanometer current: $I_g = 10\,mA = 0.01\,A$.Series multiplier resistance: $R_s = 498\,\Omega$.At full-scale deflection, the total voltage is $5\,V$, so:$V = I_g(G + R_s)$.Substitute the values:$5 = 0.01(G + 498)$.Solve for $G + 498$:$G + 498 = \frac{5}{0.01} = 500$.Therefore:$G = 500 - 498 = 2\,\Omega$.Answer:The resistance of the galvanometer is $2\,\Omega$, so the correct option is B. $2\,\Omega$.