Difference between revisions of "Electrostatics"
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= Textbook = | = Textbook = | ||
[https://openstax.org/books/university-physics-volume-2/pages/5-introduction University Physics Volume 2: Chapter 5] | [https://openstax.org/books/university-physics-volume-2/pages/5-introduction University Physics Volume 2: Chapter 5] | ||
= Electrostatics | = Theory = | ||
== Charge, Conductors, and Insulators: Introduction to Electrostatics == | |||
=== Electric Charge (q) === | |||
* '''A basic property''': Objects can have a positive or negative electric charge. | |||
* '''Types''': Positive charge (more protons than electrons), Negative charge (more electrons than protons). | |||
* '''Conservation''': Charge is neither created nor destroyed, only transferred. | |||
* '''Quantized''': <math> Q = n \cdot e </math>. Charge exists in multiples of the '''elementary charge''' <math> e = 1.6 \times 10^{-19} \, \text{C} </math>. | |||
=== Conductors === | |||
* '''Definition''': Materials where electric charges (electrons or ions) can move freely. | |||
* '''Examples''': Metals like copper and silver. Salt-Solutions. | |||
=== Insulators === | |||
* '''Definition''': Materials where charges can’t move freely. | |||
* '''Examples''': Glass, rubber, and plastic. | |||
<youtube>-Oq16ndKja8</youtube> | <youtube>-Oq16ndKja8</youtube> | ||
<br class="clear"/> | <br class="clear"/> | ||
== Coulomb's Law in Vector Form == | |||
The electrostatic force <math> \vec{F_{ts}} </math> between two point charges <math> q_s </math> (source charge) and <math> q_t </math> (test charge), separated by a distance <math> r </math>, is given by: | |||
<math> \vec{F_{ts}} = k_e \frac{q_s q_t}{r^2} \hat{r} </math> | |||
where: | |||
* <math> \vec{F_{ts}} </math>: Force (vector) on the test charge by the source charge | |||
* <math> k_e </math>: Electrostatic constant, approximately <math> 8.99 \times 10^9 \, \text{N m}^2/\text{C}^2 </math> | |||
* <math> q_s </math>: Source charge (the charge exerting the force) | |||
* <math> q_t </math>: Test charge (the charge the force is exerted on) | |||
* <math> r </math>: Distance between the charges | |||
* <math> \hat{r} </math>: Unit vector (a vector of length one) pointing from the source charge to the test charge | |||
<youtube>MwzwnhxoQh4</youtube> | <youtube>MwzwnhxoQh4</youtube> | ||
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=== Calculation Example of Coulomb's Law in Vector Form === | === Calculation Example of Coulomb's Law in Vector Form === | ||
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== Triboelectric effect/series or triboelectricity == | |||
The '''triboelectric effect''' is a phenomenon where certain materials become electrically charged after they come into contact and are then separated. This effect occurs due to friction, causing electrons to transfer between the materials. As a result, one material gains electrons (becoming negatively charged) and the other loses electrons (becoming positively charged). | |||
Different materials have varying tendencies to gain or lose electrons, which are organized in the '''triboelectric series'''. Materials higher on the series (such as glass or hair) tend to lose electrons and become positively charged, while materials lower on the series (such as rubber or Teflon) tend to gain electrons and become negatively charged. | |||
The triboelectric effect is commonly observed in everyday life, for example: | |||
* When a balloon rubbed on hair makes the hair stand up. | |||
* When synthetic clothing generates static cling. | |||
== Demonstrations | <youtube>Fph08eKTVZM</youtube> | ||
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= Demonstrations = | |||
== Bending Water == | |||
<youtube>u-SIJSSBsjo</youtube> | <youtube>u-SIJSSBsjo</youtube> | ||
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== Sticking a balloon to the wall == | |||
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Back to [[Electricity_and_Magnetism]] | Back to [[Electricity_and_Magnetism]]<br class="clear"/> | ||
Next: [[The Electric Field]] |
Latest revision as of 15:30, 22 November 2024
Back to Electricity_and_Magnetism
Textbook
University Physics Volume 2: Chapter 5
Theory
Charge, Conductors, and Insulators: Introduction to Electrostatics
Electric Charge (q)
- A basic property: Objects can have a positive or negative electric charge.
- Types: Positive charge (more protons than electrons), Negative charge (more electrons than protons).
- Conservation: Charge is neither created nor destroyed, only transferred.
- Quantized: . Charge exists in multiples of the elementary charge .
Conductors
- Definition: Materials where electric charges (electrons or ions) can move freely.
- Examples: Metals like copper and silver. Salt-Solutions.
Insulators
- Definition: Materials where charges can’t move freely.
- Examples: Glass, rubber, and plastic.
Coulomb's Law in Vector Form
The electrostatic force between two point charges (source charge) and (test charge), separated by a distance , is given by:
where:
- : Force (vector) on the test charge by the source charge
- : Electrostatic constant, approximately
- : Source charge (the charge exerting the force)
- : Test charge (the charge the force is exerted on)
- : Distance between the charges
- : Unit vector (a vector of length one) pointing from the source charge to the test charge
Calculation Example of Coulomb's Law in Vector Form
Triboelectric effect/series or triboelectricity
The triboelectric effect is a phenomenon where certain materials become electrically charged after they come into contact and are then separated. This effect occurs due to friction, causing electrons to transfer between the materials. As a result, one material gains electrons (becoming negatively charged) and the other loses electrons (becoming positively charged).
Different materials have varying tendencies to gain or lose electrons, which are organized in the triboelectric series. Materials higher on the series (such as glass or hair) tend to lose electrons and become positively charged, while materials lower on the series (such as rubber or Teflon) tend to gain electrons and become negatively charged.
The triboelectric effect is commonly observed in everyday life, for example:
- When a balloon rubbed on hair makes the hair stand up.
- When synthetic clothing generates static cling.
Demonstrations
Bending Water
Sticking a balloon to the wall
Electrostatics Simulations
Check out these links for playing with charges:
These and more links can be found at:
http://www.thephysicsteacher.ie/lcphysics19staticelectricity.html
See how lightning strikes:
Back to Electricity_and_Magnetism
Next: The Electric Field