Question

The conduction current is same as displacement current when source is :

• A. AC only
• B. DC only
• C. both AC and DC
• D. neither DC nor AC

Answer 1

Answer: (C)

Displacement current is a quantity related to a changing electric field,
it is not a real current (movement of charge) in a vacuum,
but it has the units of current as movement of charge does,
and has an associated magnetic field.
The displacement current density is mathematically defined by the rate of change of the electric displacement density $D$,
$J_D=\frac{\partial D}{\partial t}=\frac{\partial E}{\partial t}$
When an electric potential difference is placed across a conductor,
its movable charges flow giving rise to an electric current.
The conductivity a is defined as ratio of current density $J$ to electric field strength $E$ $J=\sigma E$
Hence, conduction current is same as displacement current when source is both AC and DC.