The following question are concerned with experiments of the characterization and use of a moving coil galvanometer.
The series combination of variable resistance R, one 100Ω resistor and moving coil galvanometer is connected to a mobile phone charger having negligible internal resistance. The zero of the galvanometer lies at the centre and the pointer can move 30 division full scale on either side depending on the direction of current. The reading of the galvanometer is 10 divisions and the voltages across the galvanometer and 100Ω resistor are respectively 12 mV and 16 mV.
Now a 1000 μF capacitor is charged using the 12 V supply and is discharged through the galvanometer-resistance combination used in the previous question. The current i (in ampere) at different time t (in second) are recorded. A graph of (In i) against (t) is plotted. The slope of the graph is
(A) –0.02 s–1
(B) –0.01 s–1
(C) – 0.04 s–1
(D) + 0.04 s–1
