Faraday's greatest contribution to science was in the field of electricity. In 1821 he began experimenting with electromagnetism and by demonstrating the conversion of electrical energy into motive force, invented the electric motor. In 1831 Faraday discovered the induction of electric currents and made the first dynamo. In 1837 he demonstrated that electrostatic force consists of a field of curved lines of force, and conceived a specific inductive capacity. This led to Faraday being able to develop his theories on light and gravitational systems.