Crank up the potential—and the fun! Affordable and portable, this model sets it up anywhere in the classroom. Instead of the fixed belt speed of traditional models, you control the speed with the hand crank. Demonstrate the conversion of mechanical to electrical energy, and show whether crank speed affects spark production. The 7-1/2"-diam spherical metal globe allows for continuous charge buildup (75 to 200 kV). Measures 22" H. Includes 4" discharging sphere and instructions.