4.1.1 Elementary Charge

4.1.1 Elementary Charge

by David Bittinger

​Atomic Structure

​Protons: Positive Charge, DO NOT move within matter

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​Neutrons: No charge, neutral. DO NOT move within matter

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​Electrons: Negative Charge, orbit the nucleus

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Open Ended

Based on the location of the sub-atomic particles, what pattern do you notice about the particles that are mobile (electron) and those that do not move within matter (protons, and neutrons)

​•charge: a fundamental property of matter

–measured in COULOMBS (C) or ELEMENTARY CHARGE (e)

•

•charge on an object is carried by particles

​–Electron

•-1.6 x 10-19 coulombs

•-1e

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–Proton

•+1.6 x 10-19 coulombs

•+1e

•

​

–

​Jump over to slide 4 of the ppt

​Charged Objects

​Because objects can only gain or lose electrons, the only charges that are allowed are multiples of the ELEMENTARY CHARGE

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​Neutral plate: # protons = # electrons

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​Charged plate: # protons not equal to # electrons

​Jump to slide 5 on ppt

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Multiple Choice

Example 1: An object has three excess electrons. What is its "elementary charge" and what is its charge in coulombs?

• -3e & 4.8E-19 C

• 3e & 4.8E-19 C

• -3e & -4.8E-19 C

• 3e & -4.8E-19C

​Law of Conservation of Charge

​•The total amount of charge in a closed system remains constant – charge is not created or destroyed, it only moves from one object to another

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•Charge “moves” as a result of ELECTRON movement ONLY!!!

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Multiple Choice

A metal sphere with 2 excess electrons touches a neutral metal sphere and then taken away. What do you predict the charge on each sphere will be after they make contact?

• -1.6E-19 C

• 1 e

• -3.2E-19 C

• -2 e

Multiple Choice

A metal sphere with 2 excess electrons touches a neutral metal sphere and then taken away. What is the total charge on both spheres combined after they come in contact?

• -1.6E-19 C

• -3.2E-19 C

• 1 e

• 2 e

Multiple Choice

The number of excess elementary charges on sphere A is

• 6.25E-25

• 6.4E-19

• 2.5E13

• 5.0E13