Current per unit area (taken normal to the current), l/A, is called ______.

Correct option is D

Correct Answer: (d) Current density
Explanation:
· Current density (J) is defined as the current flowing per unit area taken normal (perpendicular) to the direction of current flow.
· Formula:
J=IAJ = \frac{I}{A}J=AI​
· It tells how densely electric current is distributed across a conductor’s cross-section.
Information Booster:
· SI unit of current density = A/m².
· High current density → higher heating effect in conductors.
· Relation with conductivity:
J=σE
where σ = conductivity and E = electric field.
Additional Knowledge:
· (a) Conductivity:
· Defines how well a material conducts electricity.
· Symbol σ, unit: S/m.
· (b) Relative density:
· Ratio of density of a substance to the density of water; unrelated to current.
· (c) Resistivity:
· Opposition offered by a material to current flow.
· Symbol ρ, unit: Ω·m.