Figure shows a potentiometer with a cell of 2.0 V and internal resistance 0.40 Omega maintaining a potential drop across the resistor wire AB. A standard cell which maintains a constant emfof 1.02 V (for very moderate currents upto a few mA) gives a balance point at 67.3 cmlength of the wire. To ensure very low currents drawn from the standard cell, a very high resistance of 600 k Omegais put in series with it, which is shorted close to the balance point. The standard cell is then replaced bya cell of unknown emfe and the balance point found similarly, turns out to be at 82.3 cm length of the wire. (a) What is the value epsilon ? (b)What purpose does the high resistance of600 K Omega have ? (c) Is the balance point affected by this high resistance ? (d) Would the method work in the above situation if the driver cell of the potentiometer had an emf of 1.0V instead of 2.0 V ? (e) Would the circuit work well for determining an extremely small emf, say of the order of a few mV (such as the typical emf of a thermocouple) ? If not, how will you modify the circuit ? (f) Can we use above circuit to measure very small emf of the order of mV. (For example, emf obtained in thermocouple) ? If not, then what change would you make ?