Question

Figure 3.33 shows a potentiometer with a cell of 2.0 V and internal resistance 0.40Ω maintaining a potential drop across the resistor wire AB. A standard cell which maintains a constant emf of 1.02 V (for very moderate currents upto a few mA) gives a balance point at 67.3 cm length of the Wire. To ensure very low currents drawn from the standard cell, a very high resistance of 600 kΩ is put in series with it, which is shorted close to the balance point. The standard cell is then replaced by a cell of unknown emf 8 and the balance point found similarly, turns out to be at 82.3 cm length of the wire.What purpose does the high resistance of 600 KΩ have?

Answer 1

$\mathfrak{Hello\:User}$

We use high resistance to prevent the flow of high current through the sensitive wire of potentiometer and to protect our galvanometer because if high current flows then first galvanometer get burned and after that sensitive wire of potentiometer.

Hence we used high resistance to protect our circuit from these.