(a) Why are the connections between the resistors in a meter bridge made of thick copper strips ?
(b) Why is it generally preferred to obtain the balance point in the middle of the meter bridge wire?
(c) Which material is used for the meter bridge wire and why?
OR
A resistance of R draws current from a potentiometer as shown in the figure. The potentiometer has a total resistance Ro
. A voltage V is supplied to the potentiometer. Derive an expression for the voltage across R when the sliding contact is in the middle of the potentiometer. 
a) The resistivity of copper wire is very low. The connections between the resistors are made of thick wires so as to increase the rate of cross-section. Therefore, the resistance of wires is almost negligible.
b) Balance point is obtained in the middle of the meter bridge wire so as to increase the sensitivity of the meter bridge.
c) Constantan is used for meter bridge wire because its temperature coefficient of resistance is almost negligible due to which the resistance of the wire does not change with an increase in the temperature of the wire due to the flow of current.
OR
Total resistance is given by, Rtot = 
= 
Total current through the device is given by, Itotal = V / Rtotal
Current through resistance R is given by, I2 = Itotal x 
