In a meter bridge, point D is a neutral point as shown in the figure.
 

a. The meter bridge can have no other neutral point for this set of resistances.
b. When the jockey contacts a point on the meter wire left of D, current flows to B from the wire.
c. When the jockey contacts a point on the meter wire to the right of D, current flows from B to the wire through the galvanometer.
d. When R is increased, the neutral point shifts to left.


                                    

Which of the above statements is correct?

1. (a, c)

2. (a, d)

3. (b, c)

4. (c, d)

(1) Hint: The resistance dropped across the wire is directly proportional to its length.
At the neutral point, the potential at B and neutral points are the same. When jockey is placed at the right of D, the potential drop across AD is more than the potential drop across AB, which brings the potential of point D less than that of B, hence current flows from B to D.