Maker's Name: 
W. G. Pye & Co.
Where made: 
19 × 15 × 12 cm

Barlow's Wheel illustrates Fleming's hand rules, which show the direction of the motion of a current-carrying conductor in a magnetic field.

A star disc spins on a horizontal axis. Each tip of the star dips in turn into a pool of mercury. The disc turns between the poles of a permanent magnet. Current passes from one terminal through the star disc, through the mercury trough and out through the other terminal. The star disc rotates in a direction according to the direction of the magnetic field, and the direction of current flow (Fleming Hand Rules predict).

  • Index card