L01_viet_charge and coulomb's law

L01_viet_charge and coulomb's law - Physics 122 Electricity...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Physics 122 Electricity and Magnetism Lecture 1 Charge and Coulomb’s Law
Background image of page 1

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

View Full DocumentRight Arrow Icon
05/12/09 Physics 122 - Lecture 1 2 The History of Electricity “Rub amber with wool, and it will pick up bits of wood, feathers, straw …” Thales of Miletus (640-546 BC) About 1736, Charles Francois du Fay (1698-1739) learned that rubbing glass and rubbing resinous substances (e.g., amber) seemed to produce charges of different kinds. He found that two charges of the same kind repelled each other, while two of unlike kinds attracted. He suggested that electricity might exist as two distinctly different types, which he named “vitreous” and “resinous” electricity . Electric elektron = Greek word for amber William Watson (1715-1790) suggested in 1746 that electricity was one “fluid” . One of the two kind of electricity proposed by Du Fay could be an excess ( + ) of this fluid and the other a deficiency of it ( - ). Flow from + to - could account for electrical discharge. Benjamin Franklin (1706-1790) adopted and popularized Watson's “one fluid” theory and chose vitreous e lectricity to be the positive type (thereby giving electrons a negative charge). Franklin’s great reputation won universal acceptance for this view.
Background image of page 2
05/12/09 Physics 122 - Lecture 1 3 Charging Experiments (1) Observations: 1. No force is observed between un-rubbed rods. 2. Plastic rods rubbed with wool repel each other. 3. Glass rod rubbed with silk attracts plastic rod rubbed with wool. 4. At increased distance, forces are decreased. 1 2 4 3
Background image of page 3

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

View Full DocumentRight Arrow Icon
05/12/09 Physics 122 - Lecture 1 4 Charging Experiments (2) More Observations: 1. A (charged) plastic rod rubbed with wool attracts small pieces of paper. 2. A (charged) plastic rods rubbed with wool is attracted to an un-rubbed (neutral) plastic rod. 3. A plastic rod rubbed with wood is attracted to the wool, repelled by the silk. 4. No charged (rubbed) object attracts both the charged plastic rod and the charged glass rod. 1 2 3 4
Background image of page 4
Physics 122 - Lecture 1 5 Charging Experiments (3) Even More Observations: 1. The charge from a plastic rod rubbed with wool can be transferred to a metal sphere. 2. After the transfer, the plastic rod does not attract paper. 3. A 2 nd metal sphere connected by a metal rod acquires the rod’s charge. 4. A 2nd metal sphere connected by a plastic rod does not acquire the rod’s charge. 1
Background image of page 5

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

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/25/2009 for the course ECE 373 taught by Professor Marc during the Spring '09 term at 東京大学.

Page1 / 32

L01_viet_charge and coulomb's law - Physics 122 Electricity...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online