Mell Why do we prefer a potentiometer to measure emf of a cell rather than voltmeter?
The potentiometer is preferred over voltmeter for measurement of emf of cell because the potentiometer does not draw any current for itself from the primary circuit. Therefore it gives more accurate measurement thereby acting as an ideal voltmeter.
Why a voltmeter is not used for emf measurement?
A voltmeter cannot be used to measure the emf of a cell because a voltmeter draws some current from the cell. It employs a null method of measuring potential difference, so that when a balance is reached and the reading is being taken, no current is drawn from the source to be measured.
Can emf be measured by potentiometer?
The potentiometer is a device which can measure the potential difference without requiring current to pass through the cell or other device being tested. Thus, it is able to accurately measure the Emf of a cell.
Why do potentiometers measure potential difference or voltmeter?
Note: The potentiometer accurately measures the emf because it has zero internal resistance while voltmeter has an appreciable magnitude of resistance and when current moves through it there is a potential drop which the voltmeter measures accurately.
What is the difference between potentiometer and emf?
Key Differences: The Potentiometer is an instrument used for measuring the emf, whereas the voltmeter is a type of meter which measures the terminal voltage of the circuit. The Potentiometer accurately measures the potential difference because of zero internal resistance.
Why is a potentiometer preferred over a voltmeter to measure EMF?
Whereas, a voltmeter always draws current from the cell and measures the terminal voltage of the cell instead of the actual emf of the cell . What conclusion can you draw from the following observations on a resistor made of alloy manganin?
Which is more accurate a voltmeter or a potentiometer?
The potentiometer has a very high accuracy as compared to a voltmeter. A voltmeter has a high resistance (not infinite). When a voltmeter is connected to the terminals of a battery (emf), a small current flows through the internal resistance and voltmeter. So the potential measured is less than the actual emf.
How does a galvanometer work in a voltmeter?
A long time ago, circa 1930, voltmeters had galvanometers to indicate voltage. The galvanometer had to draw current from the source being measured to give a deflection. If the source resistance were high enough, the current drawn from the source would make the source voltage droop.