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Charging by Contact (touch): Conduction. Electrons are transferred from one object to another by contact. Only a conductor can charge a conductor. Conduction.
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Charging by Contact (touch): Conduction Electrons are transferred from one object to another by contact. Only a conductor can charge a conductor.
Conduction • Charge naturally tries to ‘spread out’. Electrons move away from a more negative area toward a more positive area, until a balance has been reached. • 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 • The Electroscope is a tool fordeterminingwhether 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) • Charging by Friction (The Electrostatic Series) -Two neutralobjectsare rubbed together, which transfers electrons resulting in charged objects. • Conduction -Electric charge can travel by touching a chargedobject to a neutralobject. -Results in a neutral object gaining a charge. -Electrons move towards the morepositiveobject - impartingcharge.
Charged object moves away – electrons redistribute - leaves fall back down.
Conduction Example: Using Negative Object e- Negative charge (excess e-) Negative charge (excess e-) • 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 e- Positive charge (lost e-) Positive charge (lost e-) • 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)