Electric Potential homework

In summary: If they are not, then you might need to contact your instructor for help.In summary, the electric potential a distance r from a point charge q is 195 V, and the magnitude of the electric field is 2870 N/C. Find the values of q and r.
  • #1
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Homework Statement


The electric potential a distance r from a point charge q is 195 V, and the magnitude of the electric field is 2870 N/C. Find the values of q and r.

Homework Equations


2780q=F
Fr=W
W/q=195

The Attempt at a Solution


Using substitution I got r=.00679 meters, which is correct. I can't substitute to find q... I have no idea what to do.
 
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  • #2
What are the equations for the electric field and electric potential at a distance r from a point charge q? Your text or class notes must have these two equations as they are quite fundamental. Hint: They both involve the constant from Coulomb's law.
 
  • #3
gneill said:
What are the equations for the electric field and electric potential at a distance r from a point charge q? Your text or class notes must have these two equations as they are quite fundamental. Hint: They both involve the constant from Coulomb's law.
Ik the equation F=(kQ1Q2)/(r^2) that's Coulomb's law. We never really did anything with fields or potentials... I found that electric field=F/q which I already have up there.
gneill said:
What are the equations for the electric field and electric potential at a distance r from a point charge q? Your text or class notes must have these two equations as they are quite fundamental. Hint: They both involve the constant from Coulomb's law.
I already have the electric field equation up there and the electric potential is U=(kQq)/r
 
  • #4
nfcfox said:
Ik the equation F=(kQ1Q2)/(r^2) that's Coulomb's law. We never really did anything with fields or potentials... I found that electric field=F/q which I already have up there.

I already have the electric field equation up there and the electric potential is U=(kQq)/r
I suspect that your method for finding the distance r was actually flawed, and your correct result was a coincidence. I say this because one of your relevant equations, Fr = W, is not correct for this situation. If F is meant to be force and W the work done, then it doesn't hold if the force varies with the distance (F is not constant so W = F⋅d doesn't hold).

Your new equation, U=(kQq)/r, gives the electric potential energy (in Joules) for a system of two charges. That's the energy required to bring them from infinity to a separation distance of r. What you need is the electric potential (in Volts) for a point charge at distance r.

The equations that you're seeking are:

##E = k \frac{q}{r^2}~~~~~~~~~~## Electric field strength (N/C)

##V = k \frac{q}{r}~~~~~~~~~~~## Electric potential (Volts)

You should verify that these equations are given in your textbook.
 

1. What is electric potential?

Electric potential is a measure of the electric potential energy per unit charge at a given point in an electric field. It is also referred to as voltage and is measured in volts (V).

2. How is electric potential calculated?

Electric potential is calculated by dividing the electric potential energy by the charge at a specific point. The formula for electric potential is V = U/Q, where V is electric potential, U is electric potential energy, and Q is charge.

3. What are the units of electric potential?

The units of electric potential are volts (V). However, it can also be expressed in other units such as joules per coulomb (J/C) or newtons per coulomb (N/C).

4. How is electric potential different from electric potential energy?

Electric potential is a measure of the electric potential energy per unit charge at a specific point, while electric potential energy is the potential energy that a charged particle has due to its position in an electric field.

5. How does the electric potential change in a circuit?

In a circuit, the electric potential decreases as the electric charges move through the circuit, from a higher potential to a lower potential. This is due to the conversion of electric potential energy into other forms, such as heat or light, as the charges flow through the circuit.

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