For a concentric-shell system, the electric flux through a centred Gaussian sphere is: +2×10⁶ V·m for 0<r< $r_A,$ -5×10⁶ V·m for $r_A<r<r_B,$ +5×10⁶ V·m for r> $r_B.$ For which finite interval of r is the electric field identically zero?
Options

Question

For a concentric-shell system, the electric flux through a centred Gaussian sphere is: +2×10⁶ V·m for 0<r< $r_A,$ -5×10⁶ V·m for $r_A<r<r_B,$ +5×10⁶ V·m for r> $r_B.$ For which finite interval of r is the electric field identically zero?

Options

G1 Physics · Accepted Answer

For a centred Gaussian sphere, E(4πr²) = Φ, so E = Φ/(4πr²). Since Φ is nonzero in every finite interval, there is no finite interval where E=0.

For a concentric-shell system, the electric flux through a centred Gaussian sphere is: +2×10⁶ V·m for 0<r<r_A, −5×10⁶ V·m for r_A<r<r_B, +5×10⁶ V·m for r>r_B. For which finite interval of r is the electric field identically zero?