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#surface charge

2 public questions tagged with this topic.

Electric Charge, Quantization and Conservation

What allows the electric field to be discontinuous across a charged surface, such as a conductor’s boundary?

**Charge conservation and quantization** govern rubbing processes where electrons transfer without creation. Total charge before and after remains equal, and any measured charge corresponds to n = q/e electrons, allowing counting of carriers from coulomb value. Surface charge density creates a field discontinuity. Inside a conductor, the field is zero, while just outside, it’s proportional to the surface charge density ( E = sigma/ε₀ ), as per Gauss’s law applied to a pillbox surface straddling the boundary. Substituting values gives Surface charge density, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Charge, Quantization and Conservation

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Electric Field and Electric Field Lines

Which property of electric charges is responsible for the fact that charges on a conductor in equilibrium reside only on

**Electric field** defined as E = F/q₀, force per unit positive test charge, unit N/C or V/m, direction along force on positive test charge. For point charge, E = k q/r² radially outward for q>0. Field lines start on positive and end on negative, density indicates strength. In electrostatic equilibrium, the electric field inside a conductor must be zero. If charges existed inside, they would create a field, causing further movement. Thus, charges redistribute to the surface, where they can maintain zero internal field due to their mobility. Substituting values gives Mobility, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Field and Electric Field Lines

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