Question

The SI unit of displacement current is ________.

• A. Coulomb
• B. Henry
• C. Ampere
• D. Faraday

Answer 1

The correct option is C

Ampere

The explanation for the correct answer:

Correct option: (C) Ampere

1. Displacement current is the rate of change of the electric displacement field.
2. Maxwell's Equation includes a term called displacement current.
3. The equation is:$I_D={ϵ}_o\frac{d{\varphi }_E}{dt}$, ${\varphi }_E$is the Electric Flux, ${ϵ}_o$ is the permittivity of free space
4. The S.I unit of displacement current is Ampere.
5. Current is a fundamental quantity.
6. Therefore, this option is correct.

Explanations for incorrect options:

Incorrect Option (A): Coulomb

1. According to Coulomb’s law, if two charges are separated by a distance ‘$r$’, and the charges are of opposite polarities as well.
2. The coulomb's force law equation is $F=k$$\frac{q_1{q}_2}{r^2}$, Here,$k$ is the proportionality constant called the Columba's law Constant. $q_{1}and{q}_2$ are the charges and $r$ is the distance between the charge.
3. Hence Coulomb is the S.I unit of charge.
4. A charge is a derived quantity.
5. Therefore, this option is incorrect.

Incorrect Option (B): Henry

1. If a current of 1 ampere flowing through a coil produces flux linkage of 1-weber turn, that coil has a self-inductance of 1 henry.‌
2. The electromotive force of 1 volt across the inductor is$V\left(t\right)=L\frac{dI}{dt}$,
   Where $v\left(t\right)$denotes the resulting voltage across the circuit, $I\left(t\right)$ is the current through the circuit, and $L$is the inductance of the circuit.
3. Hence, Henry is the S.I unit of inductance.
4. Inductance is a derived quantity.
5. Therefore, this option is incorrect.

Incorrect Option (D): Faraday

1. Electrical capacitance is the ability of a body to store an electrical charge.
2. The farad $F$ is the SI-derived unit of electrical capacitance.
3. Capacitance is a derived quantity.
4. Therefore, this option is incorrect.

The SI unit of displacement current is Ampere (A).