Question

For a fixed conductor at a fixed temperature, which of the following is not the mathematical statement of Ohm’s law?( V = potential difference, I = current, E = electric field, J = current density, = resistivity, = conductivity, l = length of conductor, A = area of conductor) *​

Answer 1

The complete question is:

For a fixed conductor at a fixed temperature, which of the following is not the mathematical statement of Ohm’s law?( V = potential difference, I = current, E = electric field, J = current density, = resistivity, = conductivity, l = length of conductor, A = area of conductor) *

(a) V ∝ I

(b) E = J ρ

(c) J = σ E

(d) R = ρ l/A

E=Jp is not the statement for Ohm's law.

All the three statements are correct:

• V=IR is the formula for Ohm's law which is shows the relationship between current, voltage and resistance. this law is one of the most basic laws and helps to calculate many other quantities such as, power, efficiency, voltage, current and resistance. Therefore this statement is correct.
• From Ohm's law:

        I=V/R

        since J=I/A = V/RA

        =El / ((pl/A)*A)

        = El/pl

        = E/p

         = σ E

Hence J = σ E, therefore this statement is also correct.

• For a wire of uniform cross-section, the resistance depends on its length l and the area A of cross-section.

        R= pl/A

        where p is the specific resistivity of the material. Therefore, this statement is also correct.

Therefore option b is not the correct one.

Answer 2

Answer:

correct option is A

Explanation:

potential difference