Mr. Ehret, Mr. Cooke Charging by Induction

Recall... Charged objects can attract neutral objects (Ex. balloon + wall) Protons are positively charged – Electrons are negatively charged Conductors allow electrons to flow freely between particles Insulators do not allow electrons to move freely A polarized object is one that has a negative terminal and a positive terminal Charging by Conduction

Induction Induction means: “Influence without contact” Charging by induction is a method used to charge an object without any physical contact Follows “Like charges repel, opposite charges attract” 3 step process - Bring charged object towards neutral object - Allow neutral object to polarize and then ground the neutral object by touching it - Stop touching the neutral object (remove ground), and pull charged object away (9:10)

Induction Diagrams The charge of the originally charged object does not matter The originally neutral object will always have the opposite charge of the originally charged object

Applications Induction can easily be seen using a gold leaf or needle electroscope

Example 1. Two neutral conducting pop cans are touching each other. A positively charged balloon is brought near one of the cans as shown below. The cans are separated while the balloon is nearby, as shown. After the balloon is removed the cans are brought back together. When touching again, can X is ____. a. positively charged b. negatively charged c. neutral d. impossible to tell

Example 2. Two neutral conducting pop cans are touching each other. A positively charged glass rod is brought near Can X as shown below. Which of the following occur as the glass rod approaches Can X? List all that apply. a. Electrons jump from the glass rod to can X. b. Electrons jump from the glass rod to can Y. c. Electrons jump from can X to the glass rod. d. Electrons jump from can Y to the glass rod. e. Protons jump from the glass rod to can X. f. Protons jump from can X to the glass rod. g.... nonsense! None of these occur.

Homework pg 489 #1-6