A copper-constantan thermocouple has thermo-electric power 40 μV/°C . One junction is 0°C while the other is at 50°C. The thermocouple is connected to a 30-0-30 galvanometer to produce a full scale deflection. If a 100Ω resistance is connected in series with the galvanometer, the galvanometer gives a deflection of 10 divisions. The figure of merit of the galvanometer is
(a) 1.3 μA/div
(b) 2.0 μA/div
(c) 2.3 μA/div
(d) 4.0 μA/div
