Electric field strength -- calculating distance from charge

In summary, the conversation discusses finding the distance from a uniform line of charge where the electric field strength changes from 1000 N/C to 4000 N/C. The relevant equation for this scenario is E=kq/r^2, and the attempt at a solution involves rearranging the equation to find the relationship between the electric field and distance. The correct answer is r~E/4.
  • #1
Iron_Man_123
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Homework Statement


At a distance D from a very long (essentially infinite) uniform line of charge, the electric field strength is 1000 N/C. At what distance from the line will the field strength to be 4000 N/C?

Homework Equations


E=kq/r2

The Attempt at a Solution


I know that E is inversely proportional like so: E~1/r2
hence by rearranging for 'r' I got: r~sqrt(1/E)
then I plugged in 4E because 4000 N/C is four times 1000 N/C: r~sqrt(q/4E)
and I got r~E/2 but the answer is E/4 and I don't know how?

Thanks in advance
 
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  • #2
HI,

You want to develop an expression for the electric field of a long line charge first. Your relevant equation doesn't fit that.
 
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  • #3
What is the relevant equation that fits this scenario then?
 

FAQ: Electric field strength -- calculating distance from charge

What is electric field strength?

Electric field strength is a measure of the force that an electric field exerts on a charged particle. It is a vector quantity, meaning it has both magnitude and direction.

How is electric field strength calculated?

Electric field strength is calculated by dividing the force exerted on a test charge by the magnitude of the charge, and then taking the limit as the distance between the two charges approaches zero. The formula for electric field strength is E = F/q, where E is the electric field strength, F is the force, and q is the magnitude of the charge.

What is the relationship between distance and electric field strength?

Electric field strength decreases as distance from a charge increases. This is because as the distance increases, the electric field lines spread out over a larger area, resulting in a weaker electric field strength.

Why is calculating distance from a charge important?

Calculating distance from a charge is important because it allows us to determine the strength of the electric field at a given point in space. This information is crucial in understanding the behavior of charged particles and can be used to design and analyze electrical systems and devices.

What units are used to measure electric field strength?

The SI unit for electric field strength is newtons per coulomb (N/C). However, other commonly used units include volts per meter (V/m) and newtons per charge (N/q).

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