5C20.33 TORQUE ON AN ELECTRIC DIPOLE

PURPOSE: To model the torque caused by the force of an external electric field acting on an electric dipole moment .

DESCRIPTION: A dipole is balanced on a rotating pivot.  The PVC and acrylic ends of the dipole are rubbed with paper towels to create an electric dipole moment with a negative and a positive seperation of charge.  The Wimshurst is used to charge the two flat conducting plates that surround the dipole and create an external electric field. The dipole is seen to torque under the influence of the electric field.

First, let's define some of these crucial terms (especially crucial if you want to pass that exam you have tomorrow....don't you remember the professor saying that there was going to be one?.....). An electric dipole moment for a pair of opposite charges of magnitude q is defined as the magnitude of the charge times the distance between them. When you place a neutral object in a uniform electric field, the net force acting on it is zero. However, if we place an electric dipole within an uniform electric field, a net torque is created that is equal to the equation shown: where p is the electric dipole moment, E is the electric field.

EQUIPMENT: The dipole, plates, pivot and Wimshurst are stored in the Electricity and Magnetism cabinets.

SETUP TIME: 1/2 hour.

REFERENCES: Dipole. (2007, June 29). In Wikipedia, The Free Encyclopedia. Retrieved 15:53, July 2, 2007, from http://en.wikipedia.org/w/index.php?title=Dipole&oldid=141320070