Transcript An uncharged metal object will experience a shift of electrons when

Electrostatics
That branch of science dealing with
resting electricity
Two Types of Electricity
1. Positive
2. Negative
Electrification – The process of adding
or removing electrons to matter
Three Methods of Electrification
1. Electrification by friction – Removal of
electrons from one object by rubbing it
with another
2. Electrification by contact – A body charged
by friction transfers the same charge to any
uncharged body upon contact
3. Electrification by induction – An
uncharged metal object will experience a
shift of electrons when brought into the
electric field of a charged object. In
this case, only electrons move.
- Requires a metallic conductor
- The opposite charge in conferred to
the uncharged metal object
Electrification by Induction
Matter may be classified by it’s conductivity:
1. Conductor – Allows free flow of electrons
2. Semiconductor – Allows an intermediate
flow of electrons
3. Nonconductors (dielectrics) – Allows no
flow of electrons
Again: Electrification by induction only
allows electrons to flow in a conductor.
This is the basis of electrical flow in a
conductor comprising a circuit
Temporary Electrification by Induction
charged body
notice the opposite charge is conferred on the ucharged object
Semi-Permanent Electrification by Induction
repelled electrons
electrons driven to
ground
grounding wire removed producing semi-permanent state
The Five Laws of Electrostatics
1. Like charges repel, unlike charges attract
2. Electric force b/w 2 objects is directly
proportional to the product of their
quantities and inversely proportional to
the square of the distance between them
3. Electrical charges reside on external
surfaces
4. The concentration of charges on a
curved surface is greatest where the
curvature is greatest
5. Only negative charges move in a
solid conductor
The Electroscope
A device used to detect electricity (including
the sign of the electrical charge) and/or
the presence of radiation
- This device can be used to demonstrate
some of the laws of electrostatics
Charging an electroscope by contact
A negatively charged bar contacts a neutral rod, the same charge present
on the bar is transferred to the electroscope (as indicated by divergence
of gold leaves)
Charging an electroscope by induction
A negatively charged bar that is brought near the rod will impose the opposite
charge, causing electrons to be repelled to the gold leaves (as indicated by
their divergence)
Static Discharge
When two bodies are separated by air
(insulation), there is a tendency for electrons
to build up and move towards a more
positive critical mass.
This accounts for lightening
- Damage from this is prevented by
connecting to ground