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QPages 141-142: Q23: HC Verma: Concepts of Physics - Volume 2 Gauss's Law Pages 141-142: Q23 Solution: Two conducting plates X and Y, each with a large surface area A …

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often assume a neutral plate has zero charge on all surfaces, ignoring electrostatic induction. Remember that the neutral plate Y will develop induced charges $+Q/2$ and $-Q/2$ on its inner and outer surfaces respectively, which is essential for correctly calculating the field cancellation outside the plates.

Two conducting plates X and Y, each with a large surface area A on one side), are placed parallel to each other, as shown in the following figure. Plate X is given a charge Q, whereas the other is kept neutral. Find a) the surface charge density at the inner surface of plate X b) the electric field at a point to the left of the plates c) the electric field at a point in between the plates and d) the electric field at a point to the right of the plates.

Step-by-Step Verified Solution

**Answer:** (a) σinner=−Q/(2A)\sigma_{inner} = -Q/(2A) (b) Eleft=0E_{left} = 0 (c) Ebetween=Q/(2Aϵ0)E_{between} = Q/(2A\epsilon_0) (d) Eright=0E_{right} = 0. **Step-by-Step Explanation:** Plate X has charge Q, plate Y is neutral. (a) Charge on inner surface of X = −Q/2-Q/2 (shared equally with Y's inner surface). (b) Left of plates: fields cancel. E = 0. (c) Between: E=Q2Aϵ0E = \frac{Q}{2A\epsilon_0}. (d) Right: fields cancel. E = 0 .

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