Question

A potentiometer is an accurate and versatile device to make electrical measurements of E.M.F. because the method involves:
$\left( a \right)$ A combination of cells, galvanometer, and resistances.
$\left( b \right)$ Cells
$\left( c \right)$ Potential gradients
$\left( d \right)$ A condition of no current flow through the galvanometer

Answer 1

Hint `As we know now the potentiometer is a device which we use to measure the electromagnetic force of the cell and also to compare it we use this. By using the principle of Wheatstone bridge and as we know no current flows through the galvanometer we will be able to tell the answer to this question.

Complete Step by Step Solution Potentiometer works on the principle of Wheatstone bridge i.e. no current flows through the meter.
A potentiometer is a right and adaptable gadget to make electrical estimations of voltage because of the strategy includes a state of no flow move through the galvanometer, the gadget might be acclimated measure electric potential, interior opposition of a cell and think about emf of 2 sources.
Once a potentiometer is connected across a circuit, in zero deflection condition the potentiometer attracts no current thus the reading of the potentiometer is accurate.

Hence the option $D$ will be correct. That is a condition of no current flow through the galvanometer.

Additional information A potentiometer could be a three-terminal device utilized in a circuit as a resistor. The input voltage is applied across the electrical device. The center contact could be a wiper (sliding contact) that slides over the electrical device providing never-ending contact with the resistor providing a variable voltage between most and minimum voltage. It is usually used as volume management and tone management in amplifiers and lots of different uses.

Note Both potentiometer & voltmeter are} accustomed to measure electric potential. However, once employing a meter there's a free fall inside the meter, that the measurements won't be correct. Potentiometer successively uses the null purpose (balance between 2 sides), the potentiometer offers correct measurement once the meter shows zero deflection. Hence, there's no free fall anyplace, and thence offers the correct worth of the electrical phenomenon (voltage).