5/3/2024
Electric Potential
Work, Energy, Electric potential Energy
At the end of the lesson, you will
be able to:
OBJECTIVES
LET’S RECALL
❑ Relate the electric potential with work,
potential energy, and electric field.
❑ Determine the electric potential
❑CHARGE
❑LAW OF CHARGES
❑COULOMB’S LAW
❑ELECTRIC FIELD
❑ELECTRIC FLUX
❑.
1
5/3/2024
CHARGE
LAW OF CHARGES
+
-
COULOMB’S LAW
𝑘𝑄1𝑄2
F= 2
𝑑
+
+
REPEL
-
+
ATTRACT
ELECTRIC FIELD
Electric force is directly
proportional to the quantity of
object 1 and object 2 and the
coulomb’s constant, inversely
proportional to the square of
distance separation.
𝐹
E= 𝑄
E=
𝑘𝑄
𝑑2
Electric Field is the ratio of coulomb force and the test
charge
ELECTRIC FIELD
ELECTRIC FLUX
Φ=E A N m2/C
Electric Flux is the rate of magnetic
field in a surface.
2
5/3/2024
LET’S CONNECT
ELECTRICAL FORCE
VS.
GRAVITATIONAL FORCE
ELECTRICAL FORCE
ELECTRICAL FORCE
Electric force is the force that pushes apart two like charges,
or that pulls together two unlike charges.
STRONG FORCE
OR
WEAK FORCE
HIDDEN MESSAGE
DRILLS !!
E
R
O
T
O
N
E
L
L
T
L
I
E
C
P
O
T
E
N
L
T
A
I
A
L
E
I
P
S
G
T
H
E
E
E
P
N
O
T
E
N
C
T
I
A
A
N
L
C
E
O
N
E
R
G
Y
U
T
E
E
C
T
R
T
D
P
E
E
T
R
I
N
I
C
H
R
A
L
R
R
R
L
T
G
E
Y
D
T
E
N
I
H
G
E
O
L
A
O
C
O
U
L
O
M
C
Y
G
N
I
T
M
M
V
S
E
L
U
O
J
A
T
A
K
I
F
G
Y
R
U
Y
R
W
B
Q
L
T
R
V
H
O
T
T
K
O
F
X
I
Q
J
N
B
I
O
A
J
J
C
K
Z
U
D
F
N
W
V
W
R
D
E
S
E
K
C
U
N
L
I
O
W
T
G
P
O
T
E
N
T
I
A
L
K
L
N
D
Q
E
C
N
E
R
E
F
F
I
D
T
E
M
U
W
E
Q
U
I
P
O
T
E
N
T
I
A
L
R
G
COULOMB
ELECTRON
FIELD
POTENTIAL
VOLT
DIFFERENCE
ENERGY
GRAVITATIONAL
PROTON
VOLTAGE
ELECTRICAL
EQUIPOTENTIAL
JOULES
UNIFORM
WORK
3
5/3/2024
HIDDEN MESSAGE
E
P
R
O
T
O
N
P
E
L
THE MESSAGE
E
E
C
L
I
T
R
L
I
E
C
O
T
E
N
L
T
A
A
L
E
I
S
G
T
H
E
E
E
P
N
O
T
E
N
C
T
I
A
A
N
L
C
E
O
N
E
R
G
Y
T
D
P
E
E
T
T
R
I
U
N
I
T
C
H
R
A
L
R
R
R
L
T
G
E
Y
D
T
E
N
B
I
H
G
E
O
L
A
O
C
O
U
L
O
M
C
Y
G
N
I
T
M
M
V
S
E
L
U
O
J
A
T
A
K
I
F
G
Y
R
U
Y
R
W
B
Q
L
T
R
V
H
O
T
T
K
O
F
X
I
Q
J
I
O
A
J
J
C
K
Z
U
D
F
N
W
V
N
W
R
D
E
S
E
K
C
U
N
L
I
O
W
G
P
O
T
E
N
T
I
A
L
K
L
N
D
Q
E
C
N
E
R
E
F
F
I
D
T
E
M
U
W
E
Q
U
I
P
O
T
E
N
T
I
A
L
R
G
T
COULOMB
ELECTRON
FIELD
POTENTIAL
VOLT
DIFFERENCE
ENERGY
GRAVITATIONAL
PROTON
VOLTAGE
ELECTRICAL
EQUIPOTENTIAL
JOULES
UNIFORM
WORK
ELECTRIC POTENTIAL
IS THE POTENTIAL
ENERGY PER UNIT
CHARGE.
ELECTRIC POTENTIAL ENERGY
Electric potential energy is the energy that is needed to move
a charge against an electric field.
LET’S DIG IN
ELECTRIC POTENTIAL ENERGY
ELECTRIC POTENTIAL ENERGY
If you pulled the positive particle
further away from the other charge,
you would have to use more energy.
The energy that you used to move
the particle away from the other
charge is stored in the particle as
electrical potential energy.
Our positive particle would be
pushed away from the plate
since they are both positively
charged.
The closer we try to move it to
the plate, the more energy we
have to put in.
So the charge would have more
electrical potential energy stored in
it.
So, the more electrical potential
energy the particle would have.
4
5/3/2024
ELECTRIC POTENTIAL ENERGY
ELECTRIC POTENTIAL ENERGY
+++++++
Electric
field
(E)
Force
(F)
Distance B
(da)
Distance B
(db)
------
ELECTRIC POTENTIAL ENERGY
Work done from A to B is equal to negative delta electric
potential energy (U).
W= Fd
F=Eq
Wa-b= - U
Fd= -(Ub-Ua)
Eq(d)= - (Ub-Ua)
-Eq(Db-Da)= Ub-Ua
-Eq(Db)+Eq(Da)= Ub-Ua
Point
B
ELECTRIC POTENTIAL ENERGY
Ub=- Eq(Db)
Ua=-Eq(Da)
W=-q V
Electric potential energy
(U)= -Eq(d)
1
LET’S PRACTICE
Point
A
A + 50 microcoulomb point charge moves
from point A to B as shown in the diagram
below. The magnitude of the electric field is
2 x 106 N/C. Point A and B are 80 cm and 20
cm above the negatively charged plate
respectively.
(a)Calculate the EPE at point A and B.
(b)How much work is done to move the
charge from point a to B?
(c)What is the EP at point A and B?
5
5/3/2024
(a) Ua= -Eq(da)
Ub= -Eq(db)
+++++++
Electric
field
(E)
A
(b) W=- U
B
------
(c) V= U/q
3
2
A + 70microcoulomb charge is located
at a point where the EP is +30 V. What
is the EPE of this charged particle?
What is the EPE of a -60micro Coulomb
charge located at an EP od +500 V?
Note:
The decrease in U, the PE is
negative.
The increase in V, the KE is
Positive, the Work is Positive
A 100 V battery is connected to two
oppositely charged parallel plates that are
separated by a distance of 10 mm.
(a)Calculate the electric field.
(b) What is the EP at a point 7 mm above
the negatively charged plate?
(c)What is the EPE of a +400 micro
Coulomb charge placed 7 mm above the
negatively charged plate?
W= -q V
Fd=-q V
E=F/q
F=Eq
𝑬𝒒𝒅 −𝒒 𝑽
So’
=
𝒒𝒅
𝑞𝑑
− 𝑽
𝑑
E=
6
5/3/2024
ELECTRIC POTENTIAL
FOR POINT CHARGE
4
Q
Compute the electric field from a electric
potential of 2.17 V if the charge will be
placed 2.08 x 10-3 m.
𝑽 = 𝑼𝒒
𝑽 = 𝒌𝑸
𝒓
𝑼 = 𝑽𝒒
𝑼 = 𝒌𝑸𝟏𝑸𝟐
𝒓
6
5
A 5 m diameter plastics sphere, used in a
static electricity demonstrate, has a
uniformly distributes 40 nC charge on its
surface. What is the electric potential near
its surface?
8
Calculate the amount of energy possessed
by 7.84 kC at a point charge where the
electric potential is 3.20 volts.
A particle with a charge of 8MC is 4m away
from the charge of 10 C. What is the electric
potential energy?
7
5/3/2024
9
What is the electric potential 25 cm from a
+6microC charge?
Things to Remember
Electric
Electric
Potential Field
𝑽 = 𝑼𝒒
𝑬 = 𝑭𝒒
𝑽 = 𝒌𝑸
𝒓
𝑬 = − 𝒅∆𝑽
Electric Potential Work
Energy
𝑼 = 𝑽𝒒
𝑼 = 𝒌𝑸𝟏𝑸𝟐
𝒓
W= −𝒒 ∆𝑽
W= 𝑭𝒅
𝑼𝒃 = −𝑬𝒒 𝒅𝒃 W= − ∆𝑽
𝑼𝒂 = −𝑬𝒒 𝒅𝒂
WORKSHEET
𝑼 = −𝑬𝒒 𝒅
1. Test Charges are typically in the nC to μC in units. What is
the electric potential 5.00 cm away from the center of a 1 cm
diameter rod that has a −3.00nC charge?
2. A demonstration Van de Graaff
generator has a 25.0 m diameter metal
sphere that produces a electric potential
of 100 V near its surface. What excess
charge occupy on the Aluminum sphere?
3. The energy of a proton is 5.0 x 10 -16 J at a certain position
in an Electric field. What is the Electric Potential at that
position?
4. An object with a test charge of + 2 x 10 -16 C is placed 10 cm
from another object with a charge of + 2 x 10 -10 C.
a) What is the energy of charges?
b) What is the electric potential at the point resides by
charges?
5. An electron starts from rest and is accelerated through a
electric potential of 20 V. How much work was done on the
electron? (express in eV).
8
5/3/2024
Still have questions?
Thank you
Go and make a difference
Arjhay Viloria Garcia (shoel)
Arjhay Viloria Garcia
Arjhay Garcia
ArjhayGarcia12
9