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Uniform electric field calculator

A-level Fields and space

The electric field strength between two parallel plates.

E = V / d

This free calculator is for A-level physics. Choose the quantity you want to find, enter the other values with their units, and it shows the working in the layout used in exams, with the answer to the number of significant figures you choose. The values shown are an example. Change them to your own.

Quantity to find

25000 V/m

Working

  1. Write the equation
    E = V / d
  2. Substitute the values
    E = 500 ÷ 0.02
  3. Calculate
    E = 25000 V/m
  4. Give the answer to 3 significant figures
    E = 25000 V/m
    In standard form: 2.50 × 104 V/m

Worked example

Find E, the electric field strength. Given: potential difference between the plates V = 500 V; plate separation d = 0.0200 m.

  1. Write the equation
    E = V / d
  2. Substitute the values
    E = 500 ÷ 0.02
  3. Calculate
    E = 25000 V/m
  4. Give the answer to 3 significant figures
    E = 25000 V/m
    In standard form: 2.50 × 104 V/m

Symbols and units

SymbolQuantitySI unit
EElectric field strengthV/m
VPotential difference between the platesV
dPlate separationm

Uniform electric field: rearranged

  • To find electric field strength: E = V / d
  • To find potential difference between the plates: V = E d
  • To find plate separation: d = V / E

Exam tip

The field is uniform away from the edges of the plates. The units V/m and N/C are the same.

Common questions

What is the formula for uniform electric field?

The equation is E = V / d, where E is the electric field strength (V/m); V is the potential difference between the plates (V); d is the plate separation (m).

What units should I use for uniform electric field?

In SI units: electric field strength in V/m, potential difference between the plates in V, plate separation in m. The calculator also accepts common alternatives such as kilometres, grams or minutes, and converts them for you.

How do I rearrange E = V / d?

Rearranging gives these forms: to find electric field strength: E = V / d. to find potential difference between the plates: V = E d. to find plate separation: d = V / E.

Practise uniform electric field questions

Press the button for a question with random numbers. Work it out on paper first, then type your answer.

Related

Read the full explanation on the Electric field strength formula page. More fields and space equations: Coulomb’s law, Electric field strength, Field of a point charge, Newton’s law of gravitation, Gravitational field strength, Gravitational potential, Orbital period, Escape velocity. See the full list on the a-level physics equation calculator page.