Happy 2018!

Upcoming Quizzes Friday, January 12th (Day 6) Monday, January 22nd (Day 3)

Need help? Come to remediation (come early to beat the crowds…) Reread your notes practice workbook questions. Saturday school!

Electricity!!! What’s a conductor? What’s an insulator?

What is electric charge? In nature, most of what we encounter is electrically neutral. This means: If the number of protons does not equal the number of electrons, we have a positive or negative charge.

Electrical charge The unit of electrical charge is the coulomb (C). The symbol Q is used to represent charge.

How do we create charge imbalance? We can do this by rubbing two substances together. Some electrons will scrape off the surface of one object and accumulate on the surface of the other.

How do we create charge imbalance? We can do this by rubbing two substances together. Some electrons will scrape off the surface of one object and accumulate on the surface of the other. When one substance loses electrons, it becomes __________ charged. When the other substance gains electrons, it becomes _________ charged.

When electrons accumulate on the surface of the balloon, do they move around?

Static Electricity Static electricity refers to electrical charges that are not moving. https://www.youtube.com/watch?v=oU8Fe6846d4

Review from last time… What is an electric charge? What is static electricity?

Fun with Pithballs! Opposites attract!!! Never ever ever forget this. A positively charged object and negatively charged object will attract. Two positively charged objects will repel. Two negatively charged objects will repel.

Fun with Pith balls!

Sample Exam Question A is positively charged So, B is ____________ charged C is ____________ charged D is ____________ charged E is ____________ charged

A is positively charged So, B is ____________ charged C is ____________ charged D is ____________ charged E is ____________ charged

Remember your lab? How did you put an electric charge on the objects?

3 methods for acquiring electric charge By Conduction: You can charge an object by putting a charged object in contact with a neutral object. The result is two objects that have the same charge.

3 methods for acquiring electric charge 2. By induction This is charging without direct contact. A charged object approaches a neutral object. The charged object remains charged, while the neutral object rearranges its charges to form positive and negative sides

3 methods for acquiring electric charge By Friction: When we rub two objects together, the electrons from one object are ”scraped” off and accumulate on the surface of the other. Different materials have varying abilities to capture or give up electrons. You start with 2 neutral objects. You finish with one positive and one negative.

How do charges work in Insulator vs conductor? Insulator Conductor

Review of charging…

Review of charging… What you start Method Contact? with What you get

Review of charging… - - - Method Contact? What you start with What you get By conduction Yes Charged meets neutral Both get same charge - - -

Review of charging… - - - - - Method Contact? What you start with What you get By conduction Yes Charged meets neutral Both get same charge By induction No Charged meets neutral Rearranges neutral’s charges - - - - + - -

Review of charging… - - - - - + - Method Contact? What you start with What you get By conduction Yes Charged meets neutral Both get same charge By induction No Charged meets neutral Rearranges neutral’s charges By friction Yes Two neutral meet Opposite charges develop - - - - + - - + -

Triboelectric series… or how well does something acquire or give up electrons? (p. 146) Plastic Sulphur Gold Nickel or copper Hard rubber (ebonite) Wood, yellow amber, resin Cotton Paper Silk Lead Wool Glass

Triboelectric series… or how well does something acquire or give up electrons? (p. 146) Plastic Sulphur Gold Nickel or copper Hard rubber (ebonite) Wood, yellow amber, resin Cotton Paper Silk Lead Wool Glass High affinity for capturing electrons (good at acquiring electrons)

Triboelectric series… or how well does something acquire or give up electrons? (p. 146) Plastic Sulphur Gold Nickel or copper Hard rubber (ebonite) Wood, yellow amber, resin Cotton Paper Silk Lead Wool Glass High affinity for capturing electrons (good at acquiring electrons, becoming negative) Likely to give up electrons (becoming positive)

Triboelectric series… or how well does something acquire or give up electrons? (p. 146) Plastic Sulphur Gold Nickel or copper Hard rubber (ebonite) Wood, yellow amber, resin Cotton Paper Silk Lead Wool Glass Copper trophy Wool cloth

Triboelectric series… or how well does something acquire or give up electrons? (p. 146) Plastic Sulphur Gold Nickel or copper Hard rubber (ebonite) Wood, yellow amber, resin Cotton Paper Silk Lead Wool Glass Glass Silk

What if you bring the same cloth next to silk? What happens?