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### Why don't charges on surface of current carrying wire move?

The entire wire feels a constant $\vec E=\rho\vec J$ field, and the constant $\vec J$ flow of current means that every bit of the surface charge that flowed tangentially to the next bit of the wire, ...

### Why electric field inside a hollow sphere on points except centre is 0?

Consider a Gaussian surface inside the hollow conducting sphere: Choose a spherical Gaussian surface with radius ( r ) (where ( r ) is less than the inner radius of the hollow sphere) and center at ...
• 68

• 36.1k
1 vote

### Why electric field lines inside are parallel inside a cylindrical capacitor?

Since the surface area of the outer cylinder wall is greater than the surface area of the inner cylinder wall while the amount of charge is equal and opposite, the field lines can’t be parallel. The ...
• 74.6k
1 vote

### Gauge invariance for the electric field

E = −∇V − ∂A/∂t B = ∇ × A A → A + ∇f V → V − ∂f/∂t When you transform E, you have to transform both the V and the A which occur in E (and note that mixed partial derivatives commute): E → −∇(...

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