Question

7. The current passes through a wire of variable cross-section in steady state
as shown the incorrect statement is
(1) current density increases in the direction of
current
(2) potential increases in the direction of the
current
(3) electric field increases in the direction of current
(4) drift speed increases in the direction of current C

Answer 1

Answer:

2) potential increases in the direction of the current

Explanation:

When a steady current flows in a metallic conductor of non-uniform cross-section, the current flowing through the conductor is constant. Current does not depend on the area of the conductor, hence it remains a constant. Current density, electric field, and drift speed are inversely proportional to the area of cross-section.

We can use the following formula in order to calculate drift velocity

I =nAvQ

Where,

I is the current flowing through the conductor which is measured in amperes

n is the number of electrons

A is the area of the cross-section of the conductor which is measured in m2

v is the drift velocity of the electrons

Q is the charge of an electron which is measured in Coulombs

When study or constant current flow in a metallic conductor of non-uniform cross-section then draft speed is

v = I/nAQ

v α I/A

As a result, with non-uniform cross-sections, drift speed will vary at different places. Only the current will remain the same

potential must decrease