
A voltmeter reads the potential difference across the terminals of an old battery as while a potentiometer reads its voltage as . The voltmeter resistance is .


Important Questions on Electrical Measuring Instruments
The figure shows a balanced Wheatstone bridge.

Two voltmeters and two resistances are connected as shown in the figure. On closing the switch , what will be the effect on the readings of the voltmeters?



Two ideal batteries and two ammeters are arranged as shown in the figure.
In the above figure, if the polarity of is reversed, then

In the figure, the voltmeter is not ideal. If the voltmeter is removed from , and then put across , what will be the effect on current ? Given



Three ammeters and of resistances and respectively, are joined as shown in the figure.
When some potential difference is applied across the terminals and their readings are and respectively, then

A battery of emf and internal resistance is connected across a long uniform wire of length and resistance per unit length . Two cells of and are connected as shown in the figure.
