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4 min read•january 6, 2023
Krish Gupta
Daniella Garcia-Loos
Krish Gupta
Daniella Garcia-Loos
An electric field is a vector field that describes the force experienced by a charged particle at a given point in space due to the presence of other charged particles.
Here are some key points about :
Every charged object has an electric field surrounding it, similar to how every object with mass has its own gravitational field. The more charge (or mass) there is, the stronger the field is. The only difference is that, while a gravitational field must be attractive, an electric field can be either attractive or repulsive. By convention, we use the direction that a positive test charge will move to draw our .
Rules for Drawing:
Try using the PhET simulation to create your own fields and notice the how the field strength changes as a function of charge and distance.
We've seen visually what look like. Now it's time to mathematically describe them.
is a measure of the electric force experienced by a charged particle at a given point in space due to the presence of other charged particles.
Here are some key points about :
The basic idea is to place a test charge at various locations in the field, measure the electrostatic force at that location, then calculate the field strength. The equation off of your reference tables for is:
where Fe is the electrostatic force found by using , and q is the charge on the test charge used to measure the field.
We can also rearrange the equation to determine EE in terms of the charge on the point charge Q
1.
The force at each location is the same. The field is uniform so E is constant everywhere and q is the same for each case. Fe=Eq, so the force must be the same.
2.
At which of the labeled points on the x-axis is the electric field zero?
Point A must have an of 0. The point must be closer to the smaller charge (Q) than the larger charge (-4Q), so it can't be D or E. It must also be where the force vectors between the test charge point in the opposite direction so that the net force is 0. Therefore, it can't be point C either. Since the (-4Q) is 4x greater than the , the point must be 2x as far from the -4Q charge as it is from the Q charge.
That only leaves A as the answer.
3.
Graph A is correct. At x = 2 and x = 4, the distance from the charges is 0, so the field strength must trend towards infinity. At x = 3, the repulsion from the 2 charges cancels out so the field must be 0 there.
Coulomb's Law
: Coulomb's Law states that the force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.Electric Field Strength
: Electric field strength refers to the force experienced by a unit positive charge placed in an electric field. It quantifies how strong or weak an electric field is at any given point.Electric Fields
: Electric fields are regions in space around charged objects where electric forces can be felt. They describe the influence that a charged object has on other charged objects in its vicinity.Electromagnetism
: Electromagnetism refers to the branch of physics that deals with the interaction between electricity and magnetism. It explains how electric currents create magnetic fields and how changing magnetic fields can induce electric currents.Lines of Force
: Lines of force refer to imaginary lines used to represent the direction and strength of electric fields around charged objects.Negative Charge
: A negative charge refers to an object that has an excess of electrons, resulting in a net negative charge.Positive Charge
: A positive charge refers to an object that has an excess of protons, resulting in a net positive charge.Volts per Meter (V/m)
: Volts per meter (V/m) is the unit used to measure electric field strength. It represents the amount of electric potential difference (voltage) experienced by a charge placed at a distance of one meter from a source.4 min read•january 6, 2023
Krish Gupta
Daniella Garcia-Loos
Krish Gupta
Daniella Garcia-Loos
An electric field is a vector field that describes the force experienced by a charged particle at a given point in space due to the presence of other charged particles.
Here are some key points about :
Every charged object has an electric field surrounding it, similar to how every object with mass has its own gravitational field. The more charge (or mass) there is, the stronger the field is. The only difference is that, while a gravitational field must be attractive, an electric field can be either attractive or repulsive. By convention, we use the direction that a positive test charge will move to draw our .
Rules for Drawing:
Try using the PhET simulation to create your own fields and notice the how the field strength changes as a function of charge and distance.
We've seen visually what look like. Now it's time to mathematically describe them.
is a measure of the electric force experienced by a charged particle at a given point in space due to the presence of other charged particles.
Here are some key points about :
The basic idea is to place a test charge at various locations in the field, measure the electrostatic force at that location, then calculate the field strength. The equation off of your reference tables for is:
where Fe is the electrostatic force found by using , and q is the charge on the test charge used to measure the field.
We can also rearrange the equation to determine EE in terms of the charge on the point charge Q
1.
The force at each location is the same. The field is uniform so E is constant everywhere and q is the same for each case. Fe=Eq, so the force must be the same.
2.
At which of the labeled points on the x-axis is the electric field zero?
Point A must have an of 0. The point must be closer to the smaller charge (Q) than the larger charge (-4Q), so it can't be D or E. It must also be where the force vectors between the test charge point in the opposite direction so that the net force is 0. Therefore, it can't be point C either. Since the (-4Q) is 4x greater than the , the point must be 2x as far from the -4Q charge as it is from the Q charge.
That only leaves A as the answer.
3.
Graph A is correct. At x = 2 and x = 4, the distance from the charges is 0, so the field strength must trend towards infinity. At x = 3, the repulsion from the 2 charges cancels out so the field must be 0 there.
Coulomb's Law
: Coulomb's Law states that the force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.Electric Field Strength
: Electric field strength refers to the force experienced by a unit positive charge placed in an electric field. It quantifies how strong or weak an electric field is at any given point.Electric Fields
: Electric fields are regions in space around charged objects where electric forces can be felt. They describe the influence that a charged object has on other charged objects in its vicinity.Electromagnetism
: Electromagnetism refers to the branch of physics that deals with the interaction between electricity and magnetism. It explains how electric currents create magnetic fields and how changing magnetic fields can induce electric currents.Lines of Force
: Lines of force refer to imaginary lines used to represent the direction and strength of electric fields around charged objects.Negative Charge
: A negative charge refers to an object that has an excess of electrons, resulting in a net negative charge.Positive Charge
: A positive charge refers to an object that has an excess of protons, resulting in a net positive charge.Volts per Meter (V/m)
: Volts per meter (V/m) is the unit used to measure electric field strength. It represents the amount of electric potential difference (voltage) experienced by a charge placed at a distance of one meter from a source.© 2024 Fiveable Inc. All rights reserved.
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