Question

A DC potentiometer has a potential gradient of 20 mV/cm. The balancing lengths for a standard cell and an unknown voltage are 75 cm and 120 cm respectively. If the standard cell voltage is 1.50 V, then the unknown voltage is

• A. 1.80 V
• B. 2.00 V
• C. 2.40 V
• D. 3.20 V

Hint:

Notice that the given potential gradient parameter (20 mV/cm) is extra information not required to solve the problem! You can find the answer directly using the ratio of the balancing lengths: \(1.5\text{ V} \times \frac{120\text{ cm}}{75\text{ cm}} = 2.4\text{ V}\).

Answer 1

The Correct Option is C