How Many Excess Electrons or Protons Does a Suspended Water Drop Have?

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Homework Help Overview

The problem involves a small drop of water suspended in an electric field, requiring the determination of the number of excess electrons or protons on the drop based on its mass and the electric field strength.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the balance of forces acting on the water drop, specifically the gravitational force and the electric force. Questions arise regarding the appropriate equations to use and how to relate the net charge to the number of excess protons or electrons.

Discussion Status

Participants are exploring the relationship between the forces acting on the drop and the charge it carries. Some guidance has been offered regarding solving for the net charge, but no consensus has been reached on the specific steps to take.

Contextual Notes

Participants are considering the mass of the water drop and the strength of the electric field as key factors in their calculations. There is an emphasis on understanding the implications of charge in the context of the problem.

arod2812
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Homework Statement


A small drop of water is suspended motionless in air by a uniform electric field that is directed upward and has a magnitude of 10800 N/C. The mass of the water drop is 3.99 x 10-9 kg. How many excess electrons or protons reside on the drop?


Homework Equations


which equation do i use? Do i need to use the mass of a proton to find the number of excess protons?


The Attempt at a Solution



F=ma; E=F/q
 
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The force from gravity acting on the rain drop, Fg=mg, will need to equal the force from the electric field, F=E*q, for the drop to stay motionless
 
And how do I solve for how much protons are present?
 
(Or electrons)

Well you're going to solve for q, so you'll know the NET charge on the raindrop. You know the charge of a SINGLE proton or electron
 

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