section_path: Operating principles/Force and torque
section_name: Force and torque
paragraph_text: Force and torque
  
  An electric motor converts electrical energy to mechanical energy through the force between two opposed magnetic fields. At least one of the two magnetic fields must be created by an electromagnet through the magnetic field caused by an electrical current.
  
  The force between a current I {\displaystyle I} in a conductor of length ℓ {\displaystyle \ell } perpendicular to a magnetic field B {\displaystyle \mathbf {B} } may be calculated using the Lorentz force law:
  
  Note: X denotes vector cross product.
  
  The most general approaches to calculating the forces in motors use tensor notation.