Question

Which of the following material offers the lowest resistivity?

wood
salt water
silver
lead

Answer 1

Lowest resistivity : silver

Step-by-step explanation:

The reciprocal of conductivity is called the resistivity of a material. Mathematically it can be written as :

`\sigma=(1)/(\rho)=R(A)/(l)`

Where

`\sigma` is the conductivity

`\rho` is the resistivity of the material

l and A are the length and the area of the material.

So, the material having highest conductivity will have lowest resistivity. Silver is the good conductor of electricity i.e. highest conductivity.

So, silver offers lowest resistivity.

Hence, the correct option is (c) " silver ".

Answer 2

Lower resistivity means higher conductivity: among these materials, the best conductor is silver, therefore it must be the material with lowest resistivity among those. We can also have a look at the value of resistivity of the different materials listed in the problem, to check our answer. The resistivities of the materials are the following:
Wood:
`1.00\cdot 10^(3) \Omega \cdot m`
Salt water:
`2.00\cdot 10^(-1) \Omega \cdot m`
Silver:
`1.59\cdot 10^(-8) \Omega \cdot m`
Lead:
`2.20\cdot 10^(-7) \Omega \cdot m`
We see that the material with lowest resistivity among those is silver, therefore the correct answer is silver.