Two wires have the same length and the same resistance but are made up of different materials. The resistivities of these materials are 3.97 Ù and 1.97 Ù. Obtain the ratio of the smaller cross-sectional area to the greater cross-sectional area.

Resistance R = r1* l/a1 = r2*l/a2 where r1 & r2 are resistivies of two wires.

So a1/a2 = r1/r2

To obtain the ratio of the smaller cross-sectional area to the greater cross-sectional area, we can use the formula:

Ratio of cross-sectional areas = (Resistivity of Material 1) / (Resistivity of Material 2)

Given that the resistivities of the two materials are 3.97 Ω and 1.97 Ω respectively, we can substitute the values into the formula:

Ratio of cross-sectional areas = 3.97 Ω / 1.97 Ω
= 2.01

Therefore, the ratio of the smaller cross-sectional area to the greater cross-sectional area is 2.01.