Electric potential and electric field

In summary, the problem involves two point charges, one positive and one negative, that are 15 cm apart on the x-axis. The question asks for the magnitude of the electric field at the point where the electric potential is zero. By setting the sum of the two electric potentials to zero and solving for the distance between the charges, x, we can find that x=0.1 cm. Plugging this value into the equation for the sum of the electric fields gives a final answer of 18000 V. However, the direction of the electric field due to both charges is the same, so the net electric field would be the sum of the absolute values of the two fields.
  • #1
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[SOLVED] Electric potential and electric field

Homework Statement



A - 10.0 nC point charge and a + 20.0nC point charge are 15 cm apart on the x-axis.
What is the magnitude of the electric field at the point on the x-axis, between the charges, where the electric potential is zero?

Homework Equations


sumE = E(of -10) + E (of 20)
E = kq/r^2
SumV = V(-10) +V(20)
V = kq/r


The Attempt at a Solution



let the distance at which V = 0 between the charge be x

SumV = V(-10) +V(20) = 0
k { (-10 *10^-9/0.15 - x) + (20 *10^-9/ x)} = 0
solve for x
x = 0.1
0.15 - x = 0.05

SumE = E(-10) +E(20)
k { (-10 *10^-9/(0.15 - x)^2) + (20 *10^-9/ (x)^2)} = SumE
substitute x = 0.1
Sum E= 18000 V

i don't think this is the right answer
i think i am doing something wrong
 
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  • #2
The directions of the electric field due to two charges is the same. So the net field is the sum of the absolute values of the two fields.
 
  • #3
thank you
 

Related to Electric potential and electric field

1. What is electric potential?

Electric potential is a measure of the electric potential energy per unit charge at a specific point in an electric field. It is often referred to as voltage.

2. How is electric potential different from electric field?

Electric potential is a scalar quantity that describes the potential energy per unit charge at a point in an electric field. In contrast, electric field is a vector quantity that describes the force per unit charge at a point in an electric field.

3. How are electric potential and electric field related?

Electric potential and electric field are related by the equation V = -Ed, where V is electric potential, E is electric field, and d is the distance between the point and the source of the electric field. In other words, the electric field is the negative gradient of the electric potential.

4. What is the unit of electric potential?

The unit of electric potential is volts (V), which is equivalent to joules per coulomb (J/C).

5. How is electric potential measured?

Electric potential is measured using a voltmeter, which is a type of electrical measuring instrument. It measures the potential difference between two points in an electric circuit.

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