Wheatstone Bridge

Three resistances , , and , each of and an unknown resistance form the four arms of a Wheatstone bridge circuit. When the resistance of is connected in parallel to , the bridge gets balanced. What is the value of ?

1.		2.
3.		4.

The resistances of the four arms in a Wheatstone’s bridge are and respectively. The emf and internal resistance of the cell are and respectively. If the galvanometer resistance is the current drawn from the cell will be:

1.		2.
3.		4.

A Wheatstone bridge is used to determine the value of unknown resistance by adjusting the variable resistance as shown in the figure. For the most precise measurement of , the resistances and :

1.	do not play any significant role.
2.	should be approximately equal to .
3.	should be approximately equal and are small.
4.	should be very large and unequal.