A bit information about Electric charge, Electric Field, Electrostatics, Charging by different ways

2. Electrostatics
GIRL SAFELY CHARGED TO
SEVERAL HUNDRED
THOUSAND VOLTS GIRL IN GREAT DANGER AT
SEVERAL THOUSAND VOLTS

3. Electrostatic Charges
A New Fundamental Physics Quantity
The charge of an electron (qe) is -1.6 x 10-19
C
The SI unit for charge is
called the coulomb (C).
Common electrostatic charges are small:
millicoulomb = mC = 10-3
C
microcoulomb = µC = 10-6
C
nanocoulomb = nC = 10-9
C
Electrostatic charge is a
fundamental quantity like
length, mass, and time.
The symbol for charge is q.
ATTRACTION AND REPULSION
The charge of an proton (qp) is 1.6 x 10-19
C

4. The Nature of Electric Charge
The Greeks first noticed electric charged by
rubbing amber with fur, then picking up bits of
matter. The Greek word for amber is elektron.
Charge is conserved, meaning it cannot be
created or destroyed, only transferred from
one location to another.
Benjamin Franklin arbitrarily called the two
kinds of charge positive and negative. In most
cases, only the negative charge is mobile.
In all atoms, electrons (qe) have negative charge
and protons (qp) have positive charge.
Discovery of charge
Like charges repel, and unlike charges
attract.
Properties of charge
Charge is quantized, meaning it comes in
discrete amounts (like money).
total charge = integer x fundamental unit of charge

5. Electric Charge
The Transfer of Charge
SILK
Glass Rod
Some materials attract electrons
more than others.

6. ElEctric chargE
thE transfEr of chargE
silK
glass rod
-+
as thE glass rod is rubbEd against silK,
ElEctrons arE pullEd off thE glass onto thE silK.

7. Electric Charge
The Transfer of Charge
SILK
Glass Rod
-
-+
+
Usually matter is charge neutral, because the number of
electrons and protons are equal. But here the silk has an
excess of electrons and the rod a deficit.

8. The Transfer of Charge
SILK
Glass Rod
-
+
+
+
+
+
Glass and silk are insulators:
charges stuck on them stay put.
---
-

9. Electric Charge
+ +
Two positively charged rods
repel each other.

10. History
600 BC Greeks first discover attractive
properties of amber when rubbed.
1600 AD Electric bodies repel as well as attract

11. Electric Forces and Electric Fields
CHARLES COULOMB
(1736-1806)
MICHAEL FARADAY
(1791-1867)

13. •Electric charges at rest (static
electricity)
•Involves electric charges, the forces
between them, and their behavior in
materials
Electrostatic
s

14. • Arise from the particles in atoms
• Alone: Billions and billions of times as
strong as the force of gravity
• In Pairs: Cancel each other out and have
no noticeable effect
Electric
Forces

15. Conservation of
Charge
•No case of the creation or destruction of net
electric charge has ever been found
•Electrons are always transferred in whole –
they cannot be divided into fractions of
electrons
Electrons are never created nor
destroyed, but are simply transferred
from one material to another

16. Charging by Friction
Materials have different affinities for
electrons.
When insulators are rubbed together, one
gives up electrons and becomes positively
charged, while the other gains electrons
and becomes negatively charged.
• plastic foodwrap that sticks to a container
• sweater pulled over your head that sparks
• laundry from the dryer that clings
Common examples of charging by friction:
A material will give up electrons to
another material below it on a
triboelectric series.
• small shocks from a doorknob after walking
on carpet with rubber-soled shoes
• balloon rubbed with hair sticks that to a wall

17. Charging by Conduction
When a charged conductor makes contact with a
neutral conductor there is a transfer of charge.
Electrons are transferred from
the rod to the ball, leaving them
both negatively charged.
Electrons are transferred from
the ball to the rod, leaving
them both positively charged.
Remember, only electrons are free to move in solids.
CHARGING NEGATIVELY CHARGING POSITIVELY
Notice that the original charged object loses some charge.

18. Charging by Induction
Step 1. A charged rod is brought
near an isolated conductor. The
influence of the charge object
polarizes the conductor but does
not yet charge it.
Step 2. The conductor is
grounded to the Earth,
allowing charge to flow out
between it and the Earth.
Induction uses the influence of one charged object to
“coerce” charge flow.