Bellringer 2/14 Which of the charges in the image is positive and which is negative? If there is an electric field pointing directly to the left, which way will a negative charge move? There is a 5.2x104 C charge next to a -2.9x103 C. The charges are 4.2 m apart. What is the value of the coulomb force between them? Is this force attractive or repulsive? If the positive charge from number 2 is the source, what is the electric field at the negative charge?

Methods of Charging I can: Name and describe at least two methods of charging I can model at least two methods of charging

Three methods of charging Friction Conduction Induction

Charging by friction Examples Sliding your feet across a carpet Combing your hair Rubbing a balloon on a fuzzy sweater

Charging by conduction What does it mean if something conducts heat? Heat moves through it easily Similar idea: charges* move through the object to distribute themselves evenly. *Chemistry connection: just like in molecules, protons never move. Electrons do all the moving in any material.

Charging by conduction Why do the electrons move from the neutral sphere to the positive aluminum plate? Think about the Coulomb force The positive charges attract the negative charges, and since both objects are conductors, the electrons can easily move from one to the other. Also, the negative charges repel each other

Charging by induction Can be similar to conduction The key difference is induction does not involve the charged object touching the neutral one.

Charging by induction This example looks really similar Notice the hand is not touching the metal sphere, just separating the two

Methods of charging Friction – Charging by rubbing two objects together Conduction – Charging by touching a charged conductor to a neutral conductor. Induction – Charging by separating charges within a neutral conductor using something charged