Electric Potential Calculator

Understanding Electric Potential Calculator

Electric potential is the potential energy per unit charge. Unlike electric field, it is a scalar quantity. The potential is positive for positive charges.

How to use this calculator

1. Enter the source charge value, usually in coulombs, into the charge field.
2. Enter the distance from the charge to the point where you want the potential, in meters.
3. Make sure the distance is greater than zero, because the formula uses division by distance.
4. Click calculate to get the electric potential in volts.

The formula explained

The formula \(V = k\frac{q}{r}\) computes the electric potential \(V\) caused by a point charge \(q\) at distance \(r\). The constant \(k\) is Coulomb's constant, about \(8.99 \times 10^9\,\mathrm{N\,m^2/C^2}\).

• V = electric potential, measured in volts \(\mathrm{V}\)
• k = Coulomb's constant, approximately \(8.99 \times 10^9\,\mathrm{N\,m^2/C^2}\)
• q = the source charge, measured in coulombs \(\mathrm{C}\)
• r = distance from the charge, measured in meters \(\mathrm{m}\)

Step by step method

1. Write down the given charge \(q\) and distance \(r\).
2. Substitute the values into \(V = k\frac{q}{r}\).
3. Multiply \(k\) by \(q\), then divide by \(r\).
4. Check the sign of the result, a positive charge gives positive potential and a negative charge gives negative potential.

Worked example

Problem. Find the electric potential at a point \(0.50\,\mathrm{m}\) from a charge of \(3.0 \times 10^{-6}\,\mathrm{C}\).

1. Use \(V = k\frac{q}{r}\).
2. Substitute the values, \(V = (8.99 \times 10^9)\frac{3.0 \times 10^{-6}}{0.50}\).
3. Compute, \(V = 5.394 \times 10^4\,\mathrm{V}\), so the potential is about \(5.4 \times 10^4\,\mathrm{V}\).

Tips and common mistakes

• Keep units in meters and coulombs, because the formula is based on SI units.
• If the charge is negative, the potential will be negative, so watch the sign when entering values.

Frequently asked questions