A2L Item 204

• Description: Identify the induced charge on the surface of a cavity in a conductor.
• Goal: Hone the concept of a conductor
• Source: 283-225, Charge induced in a neutral conductor
• Keywords: Electric Field, Electromagnetism, Induced Charge

---

The question for students:

A positive charge +Q is placed outside a neutral conductor. Inside the conductor is a cavity containing no charge. What is the net charge on the surface bounding the cavity? <div class="img-center"></div>

1. A positive charge +Q
2. A positive charge +q < +Q
3. Zero charge

4. A negative charge

   -q

   <

   +Q

5. A negative charge -Q
6. Cannot determine the charge.

---

Commentary for teachers:

Answer

(3) Students have difficulty envisioning induced charge distributions, especially when the conductor has an irregular shape.

---