# Class 12 Physics Electric Charges and Field: NCERT Solutions for Question 24

This page focuses on the detailed Electric Charges and Field question answers for Class 12 Physics Electric Charges and Field, addressing the question: 'Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude 17.0 × 10−22 C/m2. What is E:   (a) in the outer region of the first plate,   (b) in the outer region of the second plate, and   (c) between the plates?'. The solution provides a thorough breakdown of the question, highlighting key concepts and approaches to arrive at the correct answer. This easy-to-understand explanation will help students develop better problem-solving skills, reinforcing their understanding of the chapter and aiding in exam preparation.
Question 24

## Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude 17.0 × 10−22 C/m2. What is E:(a) in the outer region of the first plate,(b) in the outer region of the second plate, and(c) between the plates?

The situation is represented in the following figure.

A and B are two parallel plates close to each other. Outer region of plate A is labelled as I, outer region of plate B is labelled as III, and the region between the plates, A and B, is labelled as II.

Charge density of plate A, σ = 17.0 × 10−22 C/m2

Charge density of plate B, σ = −17.0 × 10−22 C/m2

In the regions, I and III, electric field E is zero. This is because charge is not enclosed by the respective plates.

Electric field E in region II is given by the relation,

Where,

∈0 = Permittivity of free space = 8.854 × 10−12 N−1C2 m−2

= 1.92 × 10−10 N/C

Therefore, electric field between the plates is 1.92 × 10−10 N/C.