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If some electrons are added to a positively charged conducting cone, the surface charge density of the cone will:
1. Increase
2. Decrease
3. Remain unchanged
4. Can't say

1 Answer

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Best answer
Correct Answer - Option 2 : Decrease

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:

  • Negative charge: A body having an excess of electrons.
  • We know that when electrons are added to a positively charged body, the magnitude of the charge on the body decreases.
  • Surface charge density is defined as the quantity of charge per unit area.

If ΔQ charge is contained in the elemental area Δs, the surface charge density σ will be,

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

  • When some electrons are added to a positively charged conducting cone, the total charge on the cone will decrease so the surface charge density also decreases. Hence, option 2 is correct.

Electric Charge

  • It is defined as the intrinsic property of certain fundamental particles like electrons, proton, etc, due to which they produce electric and magnetic effects.
  • Types of electric charge
    1. ​Positive charge: A body having a deficiency of electrons.
    2. ​Negative charge: A body having an excess of electrons.
  • Properties of electric charge
    • Like charges repel and unlike charges attract each other.
    • A charge is a scalar quantity.
    • If a system contains a number of point charges, then the total charge of the system is obtained simply by adding all the charges algebraically.
    • A charge is always quantized.
    • A charge will always remain conserved.
    • A charge is always associated with mass.
    • The unit of charge is the coulomb.

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