The red lines are the electric field vector at the surface of cylinder – Free A2
the red lines are the electric field vector at the surface of cylinder. what is the sign of electric flux
Answer
🔌 Sign of Electric Flux through a Cylindrical Surface
📘 Concept of Electric Flux
Electric flux is a measure of the number of electric field lines passing through a given surface. It quantifies the total electric field penetrating through a surface and is defined by the formula:
ΦE = E · A = EA cosθ
- E: Electric field strength
- A: Area vector (perpendicular to the surface)
- θ: Angle between electric field vector and area vector
🧲 Interpreting the Red Field Lines
When red lines represent the electric field vectors at the surface of a cylinder:
- If the field lines are pointing outward from the surface, the electric flux is positive.
- If the field lines are pointing inward toward the surface, the electric flux is negative.
- If the number of lines entering equals the number leaving, the net electric flux is zero.
✅ Final Answer
If all the red electric field vectors are directed inward on the surface of the cylinder, then the electric flux is:
➤ Negative
This is because electric flux is considered negative when the electric field vectors are directed opposite to the outward area vector of the surface.