Saim, Princess Kyla Mae L.
STEM 12 - Banzon
WEEK 1 : Electrostatics
Grounding - transfer of negative (-) charge to ground.
Introduction to Electricity
Electricity is a form of energy. Electricity is the flow of
electrons. When the balancing force between protons
and electrons is upset by an outside force, an atom
may gain or lose an electron. When electrons are
"lost" from an atom, the free movement of these
electrons constitutes an electric current.
History of Electricity
Benjamin Franklin (1752) - Famous for tying a key to
a kite string during a thunderstorm, proving that static
electricity and lightning were indeed, the same thing.
Alessandro Volta (1800) - Created the first electric
cell (battery) and named after the SI unit volts; Volta
soaked some paper in salt water, placed zinc and
copper on alternate sides of the paper, and watched
the chemical reaction produce an electric current;
Michael Faraday - The first to realize that an electric
current could be produced by passing a magnet
through copper wiring.
Note : A generator converts motion energy into
electricity. A motor converts electrical energy into
motion
Thomas Edison (1879) - focused on inventing a
practical light bulb, one that would last a long time
before burning out. Edison used ordinary cotton thread
that had been soaked in carbon. The filament did not
burn—instead, it became incandescent.
Note : Filament, the small wire inside the bulb that
conducts the electricity. Incandescent means glow..
Edison’s Pearl Street Power Station (September 4,
1882 @ New York City) - Owned by Thomas Edison,
started with about 85 customers in lower Manhattan
received enough power to light 5,000 lamps. Its
customers paid a lot for their electricity. In today’s
dollars, electricity cost $5 per kilowatt-hour! Today’s
electricity costs about 12.6 cents per kilowatt-hour.
Alternating Current (AC) vs. Direct Current (DC)
Nikola Tesla teamed up with engineer and
businessman George Westinghouse to patent the AC
system and provide the nation with power that could
travel long distances – a direct competition with
Thomas Edison’s DC system. Tesla later went on to
form the Tesla Electric Company, invent the Tesla Coil,
which is still used in science labs and in radio
technology today, and design the system used to
generate electricity at Niagara Falls. Now using AC,
power plants can transport electricity much farther
than before. While Edison’s DC (direct current)
plant could only transport electricity within one
square mile of his Pearl Street Power Station, the
Niagara Falls plant was able to transport electricity
over 200 miles!
Idea of Charge
Polarization - realignment of negative (-) charge and
positive (+) charge.
Positive Charge (+)
- deficiency
Negative Charge (-)
- excess
Insulators - are materials that hinder the free flow of
electrons from one particle of the element to another.
Conductors - defined as materials that allow
electricity to flow through them easily. This property of
conductors that allow them to conduct electricity is
known as conductivity.
Semi-conductors - are materials which have a
conductivity between conductors (generally metals)
and non-conductors or insulators (such as ceramics).
Coulumb’s Law
Electric Charge (Q)
➔ SI Unit: Coulumb (C)
➔ Elementary Charge constant (e) = ± 1.60×10⁻¹⁹ C
n⁰
0
p⁺
+ 1.60×10⁻¹⁹ C
e⁻
- 1.60×10⁻¹⁹ C
Net Charge
➔ > 0, not fraction
➔ must be larger number
➔ Law of Conservation of Charge
u = + ne , Q =
𝑛
𝑒
nano
×10⁻⁹
micro
×10⁻⁶
centi
×10⁻²
Electric Force (F)
➔ Vector - SI Unit: Newton (N)
➔ Interactions of 2 or more charges
a. Attractive - unlike charges (positive &
negative)
b. Repulsive - like charges (positive & positive,
negative & negative)
➔ Coulumb’s Law
F∝
𝑞1𝑞2
𝑟²
Formula for Electric Field
𝐸=
𝐹₀
𝑞₀
,𝐸=K
|𝑞|
𝑟²
WEEK 3 : Electric Flux and Gauss’s Law
Note : Doubling q₁ and q₂ makes the force raise up to factor
of 4.
Kconstant = 9.0×10⁹
𝑁𝑚²
𝑐²
Formula for Electric Force (F)
F=K
|𝑞₁𝑞₂|
𝑟²
Superposition of Electric Force (F)
1. Separation Distance - x axis/y axis, based on
pythagorean theorem
2. Magnitude of Fmn - Coulumb’s Law
3. Identify the components of all forces
Fmnx = Fmn cos θ = Fmn ( 𝑎ℎ )
Fmny = Fmn sin θ = Fmn ( ℎ𝑜 )
What is Electric Flux?
➔ The electric field can be quantitatively described
using the concept of electric flux. The word flux
comes from the Latin word fluxus meaning to flow.
Electric flux (𝛟) is a measure of the number of field
lines passing through a surface.
𝑁𝑚²
➔ SI Unit: 𝐶
➔ If the plane is normal to the flow of the electric field,
the total flux is given as
Φ
E
➔ When the same plane is tilted at an angle θ, the
projected area is given as AcosƟ and the total flux
through this surface is given as
Φ
E
Formula for Superposition of Forces
F=K
|𝑞𝑚𝑞𝑛|
𝑟𝑚𝑛²
= EA
where:
● E = the magnitude of the electric field
● A = the area of the surface through which the electric
flux is to be calculated
= EAcosθ
where:
● E = the magnitude of the electric field
● A = the area of the surface through which the electric
flux is to be calculated
● θ = the angle made by the plane and the axis parallel
to the direction of flow of the electric field
WEEK 2 : Electric Field
What is Electric Field?
➔ An Electric field can be considered an electric
property associated with each point in the space
where a charge is present in any form.
𝑁
➔ SI Unit: Newton over Coulumb ( 𝐶 )
➔ Positively charge - outward electric field
➔ Negatively charge - inward electric field
➔ When the electric field is parallel to the surface that
means that no electric field is passing normally to
the surface and hence the flux is given as
Φ
E
=0
Note : The bigger amount of theta (θ) closer to 90º, the
smaller the amount of Electric Flux (𝛟)
What is Gauss’s Law?
➔ Carl Friedrich Gauss, a German scientist,
formulated a law that relates electric field, electric
flux and electric charge.
➔ Gauss’s law states that the total electric flux
through a surface is the total electric charge qtotal
inside the surface divided by permittivity of space
𝟄₀.
ΦE =
where:
● Q = total charge
● 𝟄₀ = 8.8542 × 10⁻¹²
𝐶²
𝑁𝑚²
𝑄
𝟄₀
= Permittivity constant
➔ This means that the electric flux passing through a
closed surface is independent of the shape or area
of the surface or the radius r.
WEEK 4 : Electric Potential Energy and Electric
Potential
SI Unit: Voltage (V)
Higher Potential - Higher magnitude, closer area
Lower Potential - Further distance of area
Further positive - decrease, Closer positive increase
➔ Further negative - increase, closer negative decrease
➔
➔
➔
➔
Formula for Electric Potential Energy (Interaction)
U=K
𝑞₁𝑞₂
𝑟
Formula for Electric Potential (No Interaction)
𝑉
U = 𝑞₀
WEEK 5 : Capacitance and Dielectric
What are Capacitors?
➔ Capacitor is defined as a passive component
which is used for storing electrical energy. A
capacitor is made of two conductors that are
separated by the dielectric material. These
dielectric materials are in the form of plates which
can accumulate charges.
➔ One plate is for a positive charge while the other is
for a negative charge.
What is Capacitance?
Capacitance is the effect of the capacitor.
Capacitance is defined as the ratio of electric charge Q
to the voltage V and it is expressed as
C=
𝑄
𝑉
where:
● Q = Total charge
● C = Capacitance
● V = Voltage
Formulas for Capacitance
C=
𝑄
𝑎𝑏
, C = 𝟄₀
where:
● A = Area of each plate
● d = distance
Q = CV
where:
● Q = Total charge
● C = Capacitance
● V = Voltage
𝐴
𝑑