Leaf Electroscope: School Project

Leaf Electroscope:

Electroscope is a device to detect the pretense of charge on a body. It also give an
indication of the amount of static charge on the body.

Leaf electroscope is a simple equipment to detect the static charge presence. it has
a metal bob/metal rod to collect the charge. The other end of the rod carries two
thin aluminum foil, laid hanging from a single end.

When a charged balloon (charged by friction on hair) is brought near to the metal rod
,by induction opposite charges are induced on the rod and same changes are replied
to the other end of the rod (that is, the aluminum foils. Two foils get similar charges are repelled mechanically, showing out a visual separation.

• Suggested for students view

Demonstration of static electricity generated when a plastic bag is rubbed on hair / woolen clothing. Aluminum foil get seperated

Video time: 0:52 Min

Materials used: Jam jar, screw, paper clip, household cooking foil.
The electroscope worked better after the jar was dried in a warm oven. this will avoid leaking out of static charge

More video from http://www.youtube.com/user/uGordy7

• Suggested for students view

A PVC tube is charged by friction with a soft cloth, the aluminum foil electroscope is used to detect the static electricity charge.

Video time: 0:16 min

More from http://www.youtube.com/user/zakasilva

Van de graff generator : Describing parts

Van de graff generator is an electrostatic generator first designed in 1931. it is capable of producing potential difference of about 6 to 10 million volts. Such a high voltage is made use of to accelerate charged particles to carry out nuclear reactions.

Principle
If a charged coductor is brought into internal contact with a hollow counductor, all of its charge gets transferred to the hollow conductor, irrespective of its own potential

Construction
It consists of a spherical metal shell mounted on an insulating stand ( glass, plastic ) above the ground.
A long narrow belt of an insulating material like rubber (or silk ) is wound around two pulleys p1 and p2.
Pulley p1 is at the center of the spherical shell and p2 is at the ground level. The belt is made to rotate with the help of a motor.

Working
Positive charges are sprayed to the belt by a brush b2 near the bottom. This brush made of copper collects electrons from the rubber while it is rubbed. (copper being more electro negative than rubber), thus leaving out positive charges on the belt. b2 is earthed using a wire. The electrons thus collected in the brush b2, flows to ground.
The positive charges are carried up along the rubber belt. The collecting brush b1 on top transferes these charges
from the belt to the inner portion of the spherical shell. The charges are "Switched" to the outer sufrace of the shell instantily.
As the belt continues to rotate, more and more positive charges gets collected on the shell, which rises its potential to a high value.





Video by http://www.youtube.com/user/CarletonPhysics
Physics lab demo 3