>[!summary] In static equilibrium situation we assume the electric field to be zero inside the conductor For static situations we want the electric field to be zero so we are in equilibrium. There can be postive and negative charges present in the conductor, but to be a equilibrium they must cancel out. We know if this is true if we are **Inside charged conductor (Q)** # Conductors with Cavity ![[Pasted image 20250601114211.png]] >[!note] Explanation A electrostatic conductor will have a E = 0 always inside the conductor. All charges reside on the outside of the conductor. > Adding a cavity (Second image) we can see using a gassian surface from [[Gauss's Law]] the E is still 0. >[!warning] Note If there is no charge in the cavity the electric field will still be zero even inside the cavity. (No electric field although there is charges) If now instead there is a [[Charges]] inside the cavity, to stay in equilibrium there has to be charges present ![[Pasted image 20250601120729.png]] If we want the electric field to be zero here the charge in the gausian surface would have to to be -q