Finding Electric Field from Electric Force and Charge

AI Thread Summary
To find the electric field between two conducting plates, the equation F = qE can be used, where F is the electric force, q is the charge, and E is the electric field. In this scenario, a dust grain with a charge of 65 nC experiences a force of 19 N. The uniform electric field can be calculated by rearranging the equation to E = F/q. This approach is valid due to the assumption that the electric field between the plates is uniform. Understanding the analogy between electric and gravitational forces can help clarify the relationship between force, charge, and the electric field.
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Homework Statement


A uniform electric field exists between two conducting plates separated by 1.1mm . A dust grain with charge 65nC between the plates feels a 19N electric force.
Find the electric field.

Homework Equations





The Attempt at a Solution


Can someone please give me an equation or some pointers on this please..

 
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F=qE

This equation is a simplified version of the more complex model. It only works for uniform E-fields, and a common simplifying assumption is that a field between two conducting plates is uniform, meaning it should work fine here.

By the way, if you have a decent understanding of mechanics, often a prerequisite to electricity and magnetism, you can analogize this equation with
F=ma
In both, force on some entity is proportional to the field where the entity exists. a is a gravity field and E is an electric field. For gravity, the proportionality constant is known as mass, and for electricity, the proportionality constant is known as charge. There is one major difference of concern when using this analogy: that electric properties of an entity can be negative or positive, and so can the fields produced by electrical entities be either negative or positive. Differently, mass and the fields entities with mass produce are always positive.
 
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