Physics - Current Electricity Question with Solution | TestHub
Given below are two statements:
Assertion (A): A potentiometer is preferred over a voltmeter for measuring the EMF of a cell.
Reason (R): A potentiometer draws no current from the cell when measuring its EMF, thus measuring the true EMF.
Options:
Answer:
Solution:
A potentiometer works on the null deflection method, meaning that at the balance point, no current flows through the galvanometer or the cell whose EMF is being measured. This ensures that there is no voltage drop across the internal resistance of the cell (), allowing the potentiometer to measure the true EMF. A voltmeter, on the other hand, always draws a small current, causing a terminal potential difference () to be measured, which is slightly less than the true EMF. Thus, both Assertion and Reason are true, and Reason is the correct explanation for Assertion.
