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Charging by Induction. Mr. Ehret , Mr. Cooke. 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
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Charging by Induction Mr. Ehret, Mr. Cooke
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 https://www.youtube.com/watch?v=oXoz-eg-G9w (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.
Applications to Senior Grades • In senior grades, you will use this knowledge in learning about many different concepts in chemistry and physics. • In chemistry, you guys will learn about polarity of molecules, and how positive and negative charges interact within the periodic table in forming compounds. Plus how certain compounds act similar to charged objects we talked about today! • And who wouldn’t want to be in Mr.Kumahor’s class again!!!!
Applications to Senior Grades • In physics, you guys will be doing a whole unit on electricity and magnetism, building on the same things you’re learning right now. • Mr. Boivinwill teach you guys about all the math behind electric charges and the amount of energy that charged objects carry with them. • You will learn about current, which is the flow of the electrons and protons in these charged objects (aka their speed and direction in which they travel)
Homework • pg 489 #1-6