Chapter 21

# Chapter 21 - charges are closer to the negatively charged...

This preview shows pages 1–13. Sign up to view the full content.

Electric charge: Chapter 21 Protons have positive charge Electrons have negative charge Opposite signs attract Similar signs repel Electric field – used to calculate force

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Example: LITHIUM (Li) Atom : electrically neutral 3 protons and 3 electrons. Positive ion : missing one electron so net charge is positive Negative ion : has added electron so net charge is negative
Two positive charges or two negative charges repel each other. A positive charge and a negative charge attract each other.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Copper is a good conductor of electricity; Glass and nylon are good insulators Metal ball is charged negatively as shown in A B A C
Charging a metal sphere by induction: Charges are free to move in a conductor but are tightly bound in an insulator. The earth (ground) is a large conductor having many free charges .

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
In an insulator the charges can move slightly (called polarization of the insulator). A piece of paper is attracted to a charged comb because the positive

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: charges are closer to the negatively charged comb (in the upper figure). CHARGED COMB ATTRACTS PAPER A practical example FORCE between two charges is given by Coulomb’s Law : Coulomb’s Law Coulomb’s Law: | F | = k | Q q o | / r 2 Rearranged: | F | = | q o [k Q/r 2 ] | Gives us: F = q o E where the electric field E is: | E | = | k Q / r 2 | Electric field E ELECTRIC FIELD LINES START AND END AT ELECTRIC CHARGES An electric charge is surrounded by an electric field just as a mass is surrounded by a gravitational field. Forces on electron beam in a TV tube (CRT) F = Q E and F = m g (vector equations) Application: TV tube with electron-deflecting charged plates (orange) F = Q E An ELECTRIC DIPOLE consists of a +q and –q separated by a distance d. ELECTRIC DIPOLE MOMENT is p = q d ELECTRIC DIPOLE in E experiences a torque: τ = p d E ELECTRIC DIPOLE in E has potential energy: U = - p d E ELECTRIC DIPOLE...
View Full Document

{[ snackBarMessage ]}

### Page1 / 13

Chapter 21 - charges are closer to the negatively charged...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online