Charging by Contact touch Conduction Electrons are transferred

Charging by Contact (touch): Conduction Electrons are transferred from one object to another by contact. Only a conductor can charge a conductor.

Conduction naturally tries to ‘spread out’. Electrons move away from a more negative area toward a more positive area, until a balance has been reached. Charge When a charged conductor comes in contact with a neutral conductor, electrons move from one to the other until both have an equal charge. This is called charging by conduction.

Charging by Conduction Using a Negatively Charged Object Negatively charged metal sphere to charge a neutral needle electroscope. The negatively charged sphere has to many electrons, and those electrons want to get as far away from each other as possible. When the negative sphere comes into contact with the neutral electroscope, electrons use this as a way to get farther away from each other and move into the electroscope. In the end, the sphere still has a negative charge but it is less negative then before contact. The electroscope now has a slightly negative charge because of the increase in electrons.

Charging by Conduction Using a Positively Charged Object A positively charged aluminum plate has an excess of protons. When looked at from an electron perspective, a positively charged aluminum plate has a shortage of electrons, but the protons can not go in search of electrons because they are strongly held to the nucleus. When the positively charged aluminum plate touches the neutral sphere the electrons migrate towards the protons in the plate. The sphere now has a positive charge because the electrons left. The aluminum plate still has a positive charge but it is less positive.

The Electroscope is a tool for determining whether or not an electrical charge is present in an object. It can provide 3 kinds of measurement: -detect the presence of an electrostatic charge. -determine the type of charge on an object. -determine the amount of charge on an object.

The Electroscope (Steps) 1. Charging by Friction (The Electrostatic Series) -Two neutral objects are rubbed together, which transfers electrons resulting in charged objects. 2. Conduction -Electric charge can travel by touching a charged object to a neutral object. -Results in a neutral object gaining a charge. -Electrons move towards the more positive object - imparting charge.

Charged object moves away – electrons redistribute - leaves fall back down.

Conduction Example: Using Negative Object Negative charge (excess e-) e- Negative charge (excess e-) 1. Charged rod. 2. Charge separation in pith ball -> causes attraction 3. Pith touches rod –> electrons move towards positives 4. Charge transferred to pith -> same as rod -> repulsion

CONDUCTION – with (+) rod Positive charge (lost e-) e- Positive charge (lost e-) 1. Charged rod. 2. Charge separation in pith ball (attraction) 3. Pith touches rod – electrons move towards positives. 4. Charge transferred to pith - same as rod. (repulsion)