# Homopolar motor: Quiz

Question 1: It was first built and demonstrated by ________ in 1821 at the Royal Institution in London.
William Thomson, 1st Baron KelvinCharles-Augustin de CoulombJ. J. ThomsonMichael Faraday

Question 2: Others refer to ________ to explain the homopolar motor.
Special relativityElectromagnetismMaxwell's equationsGeneral relativity

Question 3: Homopolar motors necessarily have a single-turn ________, which limits them to very low voltages.
CoilTesla coilInductorTransformer

Question 4: The homopolar motor provides a simple demonstration of the ________.
Lorentz forceMaxwell's equationsElectromagnetismMagnetic field

Question 5: A homopolar motor has a magnetic field along the ________ and an electric current that at some point is not parallel to the magnetic field.
Rigid bodyRotationRotation around a fixed axisEarth

Question 6: People often think that field lines cannot be used to understand homopolar machines, or that the field lines rotateâ€”see ________.

Question 7: Again, where at some point along the electric loop the current in the wire is not parallel to the magnetic field, there occurs a ________ that is perpendicular to both.
ElectromagnetismMaxwell's equationsLorentz forceGauss's law for magnetism