The length of a wire of a potentiometer is , and the e.m.f. of its standard cell is volt. It is employed to measure the e.m.f. of a battery whose internal resistance is . If the balance point is obtained at from the positive end, the e.m.f. of the battery is:
- A
- B
- C, where is the current in the potentiometer wire
- D
Solution & Step-by-step Explanation
In a potentiometer, the potential gradient is given by . Assuming the potential across the wire is :
The e.m.f. of the battery is balanced at . At the balance point, no current flows through the battery being measured, so its internal resistance does not affect the balance.
The e.m.f. of the battery is balanced at . At the balance point, no current flows through the battery being measured, so its internal resistance does not affect the balance.