Statement I: In the meter bridge experiment shown in figure, the balance length AC corresponding to null deflection of the galvanometer is x. If the radius of the wire AB is doubled, the balanced length becomes 4x.
Statement II: The resistance of a wire is inversely proportional to the square of its radius.

Options

A. Statement I is true, Statement II is True, Statement II is a correct explanation for Statement I.
B. Statement I is True, Statement II is True, Statement II is not a correct explanation for Statement I.
C. Statement I is True, Statement II is False.
D. Statement I is False, Statement II is True.

Answer

D

Explanation

d. The condition for no deflection of the galvanometer is
`R_1/R_2 = R_(AC)/R_(CB)`
where `R_(AC) and R_(CB)` are the resistances of the bridge wire of
length AC and CB, respectively. If the radius of the wire AB is
doubled, the ratio `R_(AC)//R_(CB)` will remain unchanged. Hence, the
balanced length will remain the same.