Numford

ElectrostaticsClass 12, Electrostatic Potential and Capacitance

Dimensional formula of Electric potential energy

[M L2 T-2]

SymbolUE SI unitjoule (J)

The energy of a charge in an electric potential, qV. It has the dimension of energy.

Derivation

How to get the dimensional formula of electric potential energy

  1. Start from the definition: electric potential energy = electric charge × electric potential.
  2. electric charge = electric current × time, so electric charge is [A] × [T] = [T A].
  3. velocity = length / time, so velocity is [L] / [T] = [L T-1].
  4. energy = mass × velocity2, so energy is [M] × [L T-1]2 = [M L2 T-2].
  5. electric potential = energy / electric charge, so electric potential is [M L2 T-2] / [T A] = [M L2 T-3 A-1].
  6. Put in the dimension of each part: [T A] × [M L2 T-3 A-1].
  7. Add the powers of each base quantity: [M L2 T-2].
Same dimensions

Quantities with the dimensions [M L² T⁻²]

Equal dimensions do not make them the same quantity. Compare electric potential energy with the others in the full grid.

Practice

Three questions on electric potential energy

1Which of these has the same dimensions as electric potential energy?

2What is the SI unit of electric potential energy?

3Which one has different dimensions from the others?

Questions

Electric potential energy: quick answers

What is the dimensional formula of electric potential energy?

The dimensional formula of electric potential energy is [M L² T⁻²]. It comes from electric potential energy = electric charge × electric potential.

What is the SI unit of electric potential energy?

The SI unit of electric potential energy is the joule (J).

Which quantities have the same dimensions as electric potential energy?

Electric potential energy shares [M L² T⁻²] with work, energy, kinetic energy, potential energy, torque, torsional constant, gravitational potential energy, strain energy. Equal dimensions do not make them the same quantity.

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