# Distance from +4μC to Zero Potential: 24mm

• mrcotton
In summary, the conversation is discussing a diagram with two charges, +4 μC and -16 μC, 120 mm apart, and trying to find the distance from the +4 μC charge to the point between the two charges where the resultant electric potential is zero. The correct answer is 24mm, but there is confusion about using the magnitude of the charges in the potential equation. The person also realizes they made a mistake in their attempt at solving the problem and needs to take a break from physics to do some math.
mrcotton

## Homework Statement

The diagram shows two charges, +4 μC and –16 μC, 120 mm apart. What is the distance from
the +4 μC charge to the point between the two charges where the resultant electric potential is
zero?
A 24mm
B 40mm
C 80mm
D 96mm

## Homework Equations

potential equation

## Homework Statement

The correct answer is a 24mm
I get that we could simply use a 1:4 ratio and therefore r must be a fifth of the way from the 4 micro coulomb charge
However when I try and equate the formula and solve algebraicaly I seem to get the wrong answer if I put in the sign of the charges.

So my question is why do we just use the magnitude of the charges?

mrcotton said:
So my question is why do we just use the magnitude of the charges?
You seem to have written U1 = U2 when you should have used U1 + U2 = 0.

Thank you, I am a fool
I must take a break and do some maths in between my physics

## 1. What does the "+4μC" represent in the distance from +4μC to zero potential?

The "+4μC" represents the charge of the object located at the point from which the distance is being measured. In this case, the object has a positive charge of 4 microcoulombs.

## 2. How is the distance from +4μC to zero potential measured?

The distance from +4μC to zero potential is measured using a ruler or measuring tape. The object with the +4μC charge is located at one end of the ruler, and the other end is moved until the potential at that point is zero, indicating that the distance is 24mm.

## 3. What is the significance of measuring the distance from +4μC to zero potential?

The distance from +4μC to zero potential is significant in determining the strength of the electric field around the object with the +4μC charge. It also helps in understanding the behavior of electric charges and their interactions.

## 4. Can the distance from +4μC to zero potential be measured in other units?

Yes, the distance from +4μC to zero potential can be measured in other units, such as meters or centimeters. However, in this case, the distance is given in millimeters (mm).

## 5. How does the distance from +4μC to zero potential affect the electric potential energy of the object?

The distance from +4μC to zero potential has a direct effect on the electric potential energy of the object. As the distance increases, the electric potential energy decreases, and as the distance decreases, the electric potential energy increases. This relationship is described by Coulomb's Law.

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