For the potentiomeer circuit, set up as shown, the potential gradient, across the potentiometer wire, AB, is (k) volt/cm. The balancing lengths, with the gap between (i) points (1) and (3) plugged in, equal (l1) cm and (ii) points (2) and (3) plugged in, equals (l2) cm.
Assuming that the current value, as obtained through the potentiometer readings, is the correct value of current, the percentage error, in the reading of the ammeter, equals
(1) \(\frac{100}{kl_1}(I_0R_1-kl_1)\) or \(\frac{(I_0(R_1+R_2)-kl_2)100}{(kl_2)}\)
(2) \(\frac{100}{kl_2}(I_0R_1-kl_1)\) or \(\frac{100}{kl_2}[I_0R_1+kl_2]\)
(3) \(\frac{100}{kl_2}(I_0R_1-kl_1)\) or \(\frac{100}{kl_2}[I_0R_1-kl_2]\)
(4) \(\frac{100}{kl_2}(I_0R_1-kl_2)\) or \(\frac{100}{kl_1}[I_0R_1+kl_2]\)