Question

Which type of charge distribution is considered for a solid metallic sphere?
1. linear charge density
2. surface charge density
3. volume charge density
4. None of these

Answer 1

Correct Answer - Option 2 : surface charge density

CONCEPT:

Linear charge density:

• It is defined as the quantity of charge per unit length.
• Its SI unit is C/m.
• If ΔQ charge is contained in the line element Δl, the linear charge density λ will be,

​\(\Rightarrow \lambda=\frac{\Delta Q}{\Delta l}\)

Surface charge density:

• It is defined as the quantity of charge per unit area.
• Its SI unit is C/m².
• If ΔQ charge is contained in the elemental area Δs, the surface charge density σ will be,

​\(\Rightarrow \sigma=\frac{\Delta Q}{\Delta s}\)

Volume charge density:

• It is defined as the quantity of charge per unit volume.
• Its SI unit is C/m3.
• If ΔQ charge is contained in the elemental volume Δv, the volume charge density ρ will be,

​\(\Rightarrow \rho=\frac{\Delta Q}{\Delta v}\)

EXPLANATION:

• We know that in a metallic body the charge always resides at the surface because the charge can flow in a metallic body.
• So surface charge density is considered for a solid metallic sphere. Hence, option 2 is correct.