ELECTROSTATICS - CHAPTER 9 - Toronto District School Board

Grade 9 Science

1

Monarch Park Collegiate

ELECTROSTATICS - CHAPTER 9

Answer True or False _______ 1. All atoms in matter always contain electric charge. _______ 2. A static electric charge is produced where a rubbing action occurred between two objects. _______ 3. Like charges attract each other while unlike charges repel each other. _______ 4. A charged object will not attract an uncharged object. _______ 5. An object becomes negatively charged when it loses it's protons to another substance when

they come into contact with each other. _______ 6. When rubber is rubbed with cotton, the cotton will become negatively charged and the

rubber will be positively charged _______ 7. Two factors that will affect the amount of static charge produced when two different

substances come into contact with each other are: the amount of contact and the strength of a nucleus to attract electrons. _______ 8. A negative charge can be transferred from one substance to another by contact. _______ 9. A positive charge an be transferred from one substance to another by contact. _______ 10. A positive charge can be created by a negatively charge object by induction. _______ 11. A negative charge can be created by a negatively charged object by induction. _______ 12. A substance that allows electrons to move freely within it is a conductor. _______ 13 Nonmetal are good conductors of electrons (electricity). _______ 14. An ebonite rod and a glass rod are both examples of insulators. _______ 15. Dry air is an insulator. That is why there is more static electricity in winter buil up on your clothes than in summer. _______ 16. When we ground an object we connect it to the earth with an insulator. _______ 17. Your body is a good conductor of electricity. _______ 18. Conductors with pointed ends discharge electrons more efficiently than spherical conductors.

Grade 9 Science

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Monarch Park Collegiate

_______ 19. A dust particle can be attracted to a TV screen by a charging effect called induced charge separation.

20. Rewrite all the False statements above to make them correct. ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________

Grade 9 Science

3

Monarch Park Collegiate

ELECROSTATICS - DRAWINGS

CHARGING BY CONTACT

I) Complete the following drawings to show the flow of electrons as a conductor becomes charge by contact with a negatively charged ebonite rod.

neutral conductor

++ +++++++ A)

negatively charged ebonite rod close but not touching the conductor

+ -+ -+ + + + + + + - -- --- - - - - - -

B)

ebonite rod makes contact with the conductor

++ +++++++ + + +++++++

C) negatively charged conductor ++ +++++++

+ + +++++++

Grade 9 Science

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Monarch Park Collegiate

II) Complete the following drawings to show the flow of electrons as a conductor becomes charge by contact with a positively charged glass rod.

neutral conductor

++ +++++++ A)

positively charged glass rod close but not touching the conductor

+ + +++++++ ----- -

B)

glass rod makes contact with the conductor

++ +++++++ + + +++++++

C) positively charged conductor ++ +++++++

+ + +++++++

Grade 9 Science

5

Monarch Park Collegiate

CHARGING BY INDUCTION

I) Complete the following drawings to show the flow of electrons as a conductor becomes charge by induction with a negatively charged ebonite rod.

neutral conductor

++ +++++++ A)

negatively charged ebonite rod close but not touching the conductor

+ -+ -+ + + + + + + - -- --- - - - - - -

B)

conductor touched with your finger

++ +++++++

ebonite rod

+ -+ -+ + + + + + + - -- --- - - - - - -

C) Which should be removed first, the finger or the rod? Draw the last diagram that shows the final charge on the conductor and the charge on the ebonite rod.

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