Two wires of equal length, one of aluminium an the other of copper have the same resistance. Which of the two wires is lighter ? Hence explain why aluminium wires are preferred for overhead power cables.
`(rho _(AI) =2.63 xx 10 ^(-8) Omega m, rho _(Cu) =1. 72 xx 10 ^(-8) Omega m.` Relative density of `Al =2. 7 of Cu =8.9.`)

Two wires of equal length, one of aluminium and the other of copper have the same resistance. Which of the two wires is lighter ? Hence explain why aluminium wires are preferred for overhead power cables. (rho_(Al) = 2.63 xx 10^(-8) Omega m , rho_(Cu) = 1.72 xx 10^(-8) Omega m, Relative density of Al = 2.7 , of Cu = 8.9 )

A copper rod of 88cm and an aluminimum rod of unknown length have their increase in length independent of increase in temperature. The length of aluminium rod is: (alpha_(Cu) =1.7 xx 10^(-5) K^(-1) and alpha_(Al)= 2.2 xx 10^(-5) K^(-1))

Two wires of diameter 0.25 cm , one made of steel and other made of brass, are loaded as shown in the figure. The unloaded length of the steel wire is 1.5 m and that of brass is 1.0 m . Young's modulus of steel is 2.0 xx 10^(11) Pa and that of brass is 1.0 xx 10^(11) Pa. Compute the ratio of elongations of steel and brass wires. (/_\l_("steel"))/(/_\l_("brass"))=?

A rigid bar of mass 15 kg is supported symmetrically by three wires each 2.0 m long. Those at each end are of copper and the middle one is of iron. Determine the ratios of their diameters if each is to have the same tension. Y_(Cu)=1.2 xx 10 ^(11) N m ^(-2), Y_(Fe) = 1.9 xx 10 ^(11) N, ^(-2)

The current in the primary circuit of a potentiometer wire is 0.5 A. Specific resistance of wire is 4 xx 10^(-7) Omega m and area of cross section of wire is 8 xx 10^(-6) m^(2) . The potential gradient on the wire would be

A rod of length 1 and negligible mass is suspended at its two ends by two wires of steel (wire A) and aluminium (wire B) of equal lengths as shown in figure. The cross-sectional areas of wires A and B are 1.0 mm^(2) and 2.0 mm^(2) respectively. Y_("steel”) = 200 xx 10 ^(9) Nm ^(-2) and Y_("auminium”) = 70 xx 10 ^(9) Nm ^(-2)

A wire of rho_(L)=10^(-6)Omega//m is turned in the form of a circle of diameter 2m. A piece of same material is connected. In diameter AB. Then find resistance in between A and B.

Aluminium wire of length 2.2 m and a Iron wire of length 1.6 m, both of diameter 3.0 mm, are connected end to end. When stretched by a load, the net elongation is found to be 0.70 mm. Obtain the load applied. Young's modulus of aluminium Y_(Al) =70 xx 10 ^(9) Nm ^(-2) Young's modulus of iron Y_(F)=120 xx 10 ^(9) Nm ^(-2)

A potentiometer wire has length 4 m and resistance 8 Omega . The resistance that must be connected in series with the wire and an accumulator of e.m.f. 2V, so as to get a potential gradient 1 mV per cm on the wire is :

A sonometer wire of length 1.5m is made of steel. The tension in it produces an elastic strain of 1% . What is the fundamental frequency of steel if density and elasticity of steel are 7.7 xx 10^(3) kg//m^(3) and 2.2 xx 10^(11) N//m^(2) respectively ?