chapter 21 reading quiz electric potential
TRANSCRIPT
Microsoft PowerPoint - Chapter21 [Compatibility Mode]• Capacitors
and capacitance
Shown is the electric potential me
This potential is caused by electric heart. Why does the potential have this pattern, and what do these measurements tell us about the heart’s condition?
easured on the surface of a patient.
trical signals originating in the beating heart. Why does the potential have this pattern, and what do these measurements tell us about the heart’s condition?
Slide 21-1
Reading Quiz
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
What are the units of potential difference?
Slide 21-2
Reading Quiz
2. New units of the electric field were introduced in this
chapter. They are:
E. /m
F. J/C
2. New units of the electric field were introduced in this
Slide 21-3
2. New units of the electric field were introduced in this
chapter. They are:
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
2. New units of the electric field were introduced in this
Slide 21-4
Reading Quiz
A. is constant.
B. increases linearly from the negative to the positive plate.
C. decreases linearly from the negative to the positive plate.
D. decreases inversely with distance from the negative plate.
E. decreases inversely with the square of the distance from
the negative plate.
the negative plate.
increases linearly from the negative to the positive plate.
decreases linearly from the negative to the positive plate.
decreases inversely with distance from the negative plate.
decreases inversely with the square of the distance from
Slide 21-5
B. increases linearly from the negative to the positive plate.
Answer
The electric potential inside a parallel-plate capacitor
increases linearly from the negative to the positive plate.
Slide 21-6
Reading Quiz
C. always bisects an equipotential surface.
D. makes an angle to an equipotential surface that depends
on the amount of charge.
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
is always perpendicular to an equipotential surface.
is always tangent to an equipotential surface.
always bisects an equipotential surface.
makes an angle to an equipotential surface that depends
on the amount of charge.
Slide 21-7
Answer
is always perpendicular to an equipotential surface.
Slide 21-8
Potential Energy
B
10
11
12
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
The potential energy per unit charge is called the electric potential. The potential energy per unit charge
13
The Electric Potential Difference
DEFINITION OF ELECTRIC POTENTIAL
The electric potential at a given point is the electric potential energy of a small test charge divided by the charge itself:
oq V
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
SI Unit of Electric Potential: joule/coulomb = volt (V)
o
DEFINITION OF ELECTRIC POTENTIAL
The electric potential at a given point is the electric potential energy of a small test charge divided by the charge itself:
EPE
U elec
Is the change U of the particle positive, negative, or
zero as it moves from i to f?
of the particle positive, negative, or
zero as it moves from i to f?
Slide 21-11
Graphical Representations of Electric Potential
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Graphical Representations of Electric Potential
Slide 21-13
Checking Understanding
potentials at the numbered points.
Rank in order, from largest to smallest, the electric
potentials at the numbered points.
Slide 21-14 Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley. Slide 21-15
Example
A proton has a speed of 3.5 x 105
electrical potential is 600 V. It moves through a point where the electric potential is 1000 V. What is its speed at this second point?
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
5 m/s at a point where the electrical potential is 600 V. It moves through a point where the electric potential is 1000 V. What is its speed at this second point?
Slide 21-16
Example
A proton is released from rest at p What is its speed at point b?
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
t point a. It then travels past point b.
Slide 21-17
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
V = Ex = Q
Q
Example
A parallel-plate capacitor is held at a potential difference of 250 V.
A proton is fired toward a small hole in the negative plate with a speed of 3.0 x 105 m/s. What is its speed when it emerges through the hole in the positive plate? (Hint: The electric potential outside of a parallel-plate capacitor is zero).
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
plate capacitor is held at a potential difference of 250 V.
A proton is fired toward a small hole in the negative plate with a m/s. What is its speed when it emerges through
the hole in the positive plate? (Hint: The electric potential outside plate capacitor is zero).
Slide 21-19
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
V = K q
1
Electric Potential: Charged Sphere
Outside of a sphere of charge Q th for a point charge Q:
V = 1
4π
If the sphere has radius R and the potential at its surface is
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
If the sphere has radius R and the potential at its surface is the potential a distance r from its center can also be written
V = R
1
Q
r
and the potential at its surface is V0, then and the potential at its surface is V0, then from its center can also be written
R V
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
A. The potential at points a and b.The potential difference between a and b.
B. The potential energy of a proton at a and b.
C. The speed at point b of a proton that was moving to the right at point a with a speed of 4.0 x 10
D. The speed at point a of a proton that was moving to the left at point b with a speed of 4.0 x 10
For the situation shown in the figure, find
The potential at points a and b.The potential difference between
The potential energy of a proton at a and b.
The speed at point b of a proton that was moving to the right at 105 m/s.
The speed at point a of a proton that was moving to the left at 105 m/s.
Slide 21-22
A 2.0-mm-diameter plastic bead is charged to
A. A proton is fired at the bead from far away with a speed of
1.0 x 106 m/s, and it collides head speed?
B. An electron is fired at the bead from far away. It “reflects,” with a turning point 0.10 mm from the surface of the bead.
What was the electron’s initial speed?
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
diameter plastic bead is charged to –1.0 nC.
A proton is fired at the bead from far away with a speed of
m/s, and it collides head-on. What is the impact
An electron is fired at the bead from far away. It “reflects,” with a turning point 0.10 mm from the surface of the bead.
What was the electron’s initial speed?
Slide 21-23
Connecting Potential and Field
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Potential and Field for Three Important Cases
Slide 21-25
A. What is the potential at point A? At which point, A, B, or C,
does the electric field have its largest magnitude?
B. Is the magnitude of the electric
field at A greater than, equal
Example
potential shown.
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
field at A greater than, equal to, or less than at point D?
C. What is the approximate magnitude of the electric field at
point C?
D. What is the approximate direction of the electric field at
point C?
does the electric field have its
Is the magnitude of the electric
Source charges create the electric
What is the approximate magnitude of the electric field at
What is the approximate direction of the electric field at
Slide 21-26
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
A Conductor in Electrostatic Equilibrium
Slide 21-27
What is Q2??
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Capacitance and Capacitors
Q = CV
is proportional to the potential difference VC between the electrodes:
Q = CV C
The Capacitance of a Parallel
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
The Capacitance of a Parallel-Plate Capacitor
C = ε
0 A
Dielectric Constant
With a dielectric between its plates, the capacitance of a parallel-plate capacitor is increased by a factor of the dielectric constant κ:
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
C = κε
0 A
Shown is the electric potential me
This potential is caused by electric heart. Why does the potential have this pattern, and what do these measurements tell us about the heart’s condition?
easured on the surface of a patient.
trical signals originating in the beating heart. Why does the potential have this pattern, and what do these measurements tell us about the heart’s condition?
Slide 21-1
Reading Quiz
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
What are the units of potential difference?
Slide 21-2
Reading Quiz
2. New units of the electric field were introduced in this
chapter. They are:
E. /m
F. J/C
2. New units of the electric field were introduced in this
Slide 21-3
2. New units of the electric field were introduced in this
chapter. They are:
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
2. New units of the electric field were introduced in this
Slide 21-4
Reading Quiz
A. is constant.
B. increases linearly from the negative to the positive plate.
C. decreases linearly from the negative to the positive plate.
D. decreases inversely with distance from the negative plate.
E. decreases inversely with the square of the distance from
the negative plate.
the negative plate.
increases linearly from the negative to the positive plate.
decreases linearly from the negative to the positive plate.
decreases inversely with distance from the negative plate.
decreases inversely with the square of the distance from
Slide 21-5
B. increases linearly from the negative to the positive plate.
Answer
The electric potential inside a parallel-plate capacitor
increases linearly from the negative to the positive plate.
Slide 21-6
Reading Quiz
C. always bisects an equipotential surface.
D. makes an angle to an equipotential surface that depends
on the amount of charge.
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
is always perpendicular to an equipotential surface.
is always tangent to an equipotential surface.
always bisects an equipotential surface.
makes an angle to an equipotential surface that depends
on the amount of charge.
Slide 21-7
Answer
is always perpendicular to an equipotential surface.
Slide 21-8
Potential Energy
B
10
11
12
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
The potential energy per unit charge is called the electric potential. The potential energy per unit charge
13
The Electric Potential Difference
DEFINITION OF ELECTRIC POTENTIAL
The electric potential at a given point is the electric potential energy of a small test charge divided by the charge itself:
oq V
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
SI Unit of Electric Potential: joule/coulomb = volt (V)
o
DEFINITION OF ELECTRIC POTENTIAL
The electric potential at a given point is the electric potential energy of a small test charge divided by the charge itself:
EPE
U elec
Is the change U of the particle positive, negative, or
zero as it moves from i to f?
of the particle positive, negative, or
zero as it moves from i to f?
Slide 21-11
Graphical Representations of Electric Potential
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Graphical Representations of Electric Potential
Slide 21-13
Checking Understanding
potentials at the numbered points.
Rank in order, from largest to smallest, the electric
potentials at the numbered points.
Slide 21-14 Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley. Slide 21-15
Example
A proton has a speed of 3.5 x 105
electrical potential is 600 V. It moves through a point where the electric potential is 1000 V. What is its speed at this second point?
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
5 m/s at a point where the electrical potential is 600 V. It moves through a point where the electric potential is 1000 V. What is its speed at this second point?
Slide 21-16
Example
A proton is released from rest at p What is its speed at point b?
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
t point a. It then travels past point b.
Slide 21-17
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
V = Ex = Q
Q
Example
A parallel-plate capacitor is held at a potential difference of 250 V.
A proton is fired toward a small hole in the negative plate with a speed of 3.0 x 105 m/s. What is its speed when it emerges through the hole in the positive plate? (Hint: The electric potential outside of a parallel-plate capacitor is zero).
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
plate capacitor is held at a potential difference of 250 V.
A proton is fired toward a small hole in the negative plate with a m/s. What is its speed when it emerges through
the hole in the positive plate? (Hint: The electric potential outside plate capacitor is zero).
Slide 21-19
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
V = K q
1
Electric Potential: Charged Sphere
Outside of a sphere of charge Q th for a point charge Q:
V = 1
4π
If the sphere has radius R and the potential at its surface is
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
If the sphere has radius R and the potential at its surface is the potential a distance r from its center can also be written
V = R
1
Q
r
and the potential at its surface is V0, then and the potential at its surface is V0, then from its center can also be written
R V
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
A. The potential at points a and b.The potential difference between a and b.
B. The potential energy of a proton at a and b.
C. The speed at point b of a proton that was moving to the right at point a with a speed of 4.0 x 10
D. The speed at point a of a proton that was moving to the left at point b with a speed of 4.0 x 10
For the situation shown in the figure, find
The potential at points a and b.The potential difference between
The potential energy of a proton at a and b.
The speed at point b of a proton that was moving to the right at 105 m/s.
The speed at point a of a proton that was moving to the left at 105 m/s.
Slide 21-22
A 2.0-mm-diameter plastic bead is charged to
A. A proton is fired at the bead from far away with a speed of
1.0 x 106 m/s, and it collides head speed?
B. An electron is fired at the bead from far away. It “reflects,” with a turning point 0.10 mm from the surface of the bead.
What was the electron’s initial speed?
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
diameter plastic bead is charged to –1.0 nC.
A proton is fired at the bead from far away with a speed of
m/s, and it collides head-on. What is the impact
An electron is fired at the bead from far away. It “reflects,” with a turning point 0.10 mm from the surface of the bead.
What was the electron’s initial speed?
Slide 21-23
Connecting Potential and Field
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Potential and Field for Three Important Cases
Slide 21-25
A. What is the potential at point A? At which point, A, B, or C,
does the electric field have its largest magnitude?
B. Is the magnitude of the electric
field at A greater than, equal
Example
potential shown.
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
field at A greater than, equal to, or less than at point D?
C. What is the approximate magnitude of the electric field at
point C?
D. What is the approximate direction of the electric field at
point C?
does the electric field have its
Is the magnitude of the electric
Source charges create the electric
What is the approximate magnitude of the electric field at
What is the approximate direction of the electric field at
Slide 21-26
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
A Conductor in Electrostatic Equilibrium
Slide 21-27
What is Q2??
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Capacitance and Capacitors
Q = CV
is proportional to the potential difference VC between the electrodes:
Q = CV C
The Capacitance of a Parallel
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
The Capacitance of a Parallel-Plate Capacitor
C = ε
0 A
Dielectric Constant
With a dielectric between its plates, the capacitance of a parallel-plate capacitor is increased by a factor of the dielectric constant κ:
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
C = κε
0 A