Van De Graff Generator

Principle of Van De Graff Generator: If a charged conductor is placed inside a hollow conductor and is connected by some medium then all the charge present inside a hollow conductor is transferred to the hollow conductor.

Construction and Working of Van De Graff Generator :

• Metal Brush : There are two metal brush one metal deliver charge to the belt other metal receive charge from belt and transfer it into the shell
• Belt : Belt is normally made of silk or rubber it transfer charge (we talking about charge not current )
• Pulley : There are two pulley on which belt is mount
• Motor : to drive the pulley
• Insulating supporting Column
• Hollow Sphere

In this motor starts it rotates the pulley at the lower end of the pulley metal brush is placed which receives positive charge this charge is sprayed on the belt via metal brush . The belt then transfer this charge to the top of the metal brush which when recieve this charge transfer it into the hollow sphere. The positive charge then spread throughout the hollow sphere outer surface uniformly.With the help Van De Graff Generator you can produce 6 to 8 million Volts with respect to ground

To calculate the Capacitance of electrical sphere we can use this formula

$C = 4 \pi \mu R$

Q = The charge in the spherical shell

C = Capacitance

R = Radius of the Sphere

μ  = Permittivity of the free space