Finding the magnitude of an electric field.

In summary, we have two charges, -8.1μC and 8.9μC, 8.0cm apart. The magnitude of the electric field at a point midway between them can be found using the formula E=k/r^2(Q1+Q2). The direction of the electric field is towards the negative charge, as both charges contribute to the electric field in that direction. Plugging in the values, we get E=2.4e7 N/C, but this is incorrect because the distance between the charges is 0.04m, not 0.08m. Therefore, the correct magnitude of the electric field is 6.0e7 N/C, rounded to two significant figures.
  • #1
atn9200
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Homework Statement


Determine the magnitude of the electric field at a point midway between a -8.1μC and a 8.9μC charge 8.0cm apart. Assume no other charges are nearby.
Determine the direction.
(Answer in two sig figs.)

Homework Equations


E=k/r^2(Q1+Q2)

The Attempt at a Solution



I drew this: -8.1---------p----------8.9

This is what I think I'm supposed to do.

The field due to -8.1 charge points toward it.
The field due to 8.9 points away. So they are both pointing towards the negative charge?

so E=k/.08^2(8.1e-6+8.9e-6)=2.4e7 N/C but this is incorrect. Please explain why! Thanks.
 
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  • #2
I want to slap myself now...is it because r=.04m? Want assurance because I'm on my last strike.
 

Related to Finding the magnitude of an electric field.

1. What is the definition of electric field magnitude?

The electric field magnitude is a measure of the strength of an electric field at a particular point in space. It is defined as the force per unit charge that would be experienced by a positive test charge placed at that point.

2. How is the magnitude of an electric field calculated?

The magnitude of an electric field can be calculated using the equation E = F/q, where E is the electric field, F is the force exerted on the test charge, and q is the magnitude of the test charge. It can also be calculated by dividing the voltage difference between two points by the distance between those points.

3. What is the unit of measurement for electric field magnitude?

The unit of measurement for electric field magnitude is newtons per coulomb (N/C) in the SI (International System of Units) system. In the CGS (centimeter-gram-second) system, the unit is dynes per electrostatic unit (dyn/esu).

4. How does the magnitude of an electric field affect charged particles?

The magnitude of an electric field determines the force that a charged particle will experience when placed in that field. The larger the electric field magnitude, the greater the force on the particle. This force can either attract or repel the charged particle, depending on the sign of the charge.

5. What factors can affect the magnitude of an electric field?

The magnitude of an electric field can be affected by the distance between two charged objects, the magnitude of the charges on those objects, and the medium between them. It can also be affected by the presence of other charged objects in the vicinity, as well as the orientation and shape of the objects creating the electric field.

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