30 Jun, 2013
PRESENTATION: While rubbing 2 objects, a charge-transfer takes place and then charged materials are converted into neuter ones.
- The Electric Whirl in the 19th and 21st Centuries, John A. Daffron and Thomas B. Greenslade, Phys. Teach. 50, 536 (2012)
INTRODUCTION: Electrostatics studies the electrical forces produced by charge distributions by means of concepts such as electrostatic field and electric potential and of laws of physics such as Coulom’s law. Historically, electrostatics was the branch of electromagnetism that first developed. Later on, Maxwell’s laws made it possible to demonstrate that the electrostatic laws and the laws governing the magnetic phenomena can be jointly studied in a same theoretical field called electromagnetism.
OBJECTIVE: To check the interaction between two bodies electrostatically charged.
MATERIALS: thread, hanger, ruler, cloth.
SET UP: We tie the ends of the cord to the ends of the ruler trying to place them as symmetrically as possible with respect to the centre so that the rule stays in a horizontal position. We hang the ruler on the hanger by the cord and start rubbing the marker against the piece of cloth during some seconds. Once the ruler has been electrostatically charged we approach it to one end of the ruler and observe that an attraction between the two objects is produced and this makes the ruler turn on its own axis.
EXPLANATION: When we rub the marker against the cloth it gets electrified because a part of the electrons of the atoms of the cloth become part of the atoms of the marker. Thus the atoms of the marker become negative atoms or anions. Therefore an attraction is produced when the approach the marker to the ruler, which is already electrostatically charged.
- WIKIPEDIA 1
- WIKIPEDIA 2
- MASSACHUSETTS INSTITUTE OF TECHNOLOGY
- UNIVERSIDAD MICHOACANA
- WAKE FOREST UNIVERSITY
- UNIVERSITY OF WISCONSIN
- WASHINGTON STATE UNIVERSITY
- R. Serway, Física, Mac Graw Hill, 2010.
- P. Tipler, Física para la Ciencia y la tecnología, Reverté, 2012.
- R. Ehrlich, Turning the World Inside Out and 174 Other Simple Physics Demonstrations, Princeton University Press, 1997.
STUDENTS 2012-2013: Alexandre De Tellitu, Manuel Fernández, Yeray Doporto.
LINK pdf STUDENTS (In Spanish):