A2L Item 206
- Description: Identify the total surface charge density on a charged cylindrical conductor with a charged wire lying along its axis.
- Goal: Reason regarding induced charges and fields
- Source: 283-235 Induced charge in conductors
- Keywords: Distributed Charges, Electromagnetism, Induced Charge
The question for students:
A positive charge per unit area σ is placed on a cylindrical conductor of inner radius, r = a, and outer radius, r = b. A positive charge per unit length, λ, is placed along the axis of the cylinder. What is the charge density (charge per area) on the outer surface?
- +λ
- +σ
- -λ
- -σ
- σ+λ/(2πa)
- σ-λ/(2πa)
- σ+λ/(2πb)
- σ-λ/(2πb)
- None of the above
Commentary for teachers:
Answer
(7) The biggest problem for students is finding the induced surface charge density due to the line charge density.