Electric Force

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2
Electric Force

• If the separation between two particles is
  doubled, what happens to the force?
• Answer 1

3
Electric Force

• The force is 1/4 of original

4
Electric Force

• The electron and proton of a hydrogen atom are
  separated by the distance of 4.9 x 10-11m. Find
  the magnitude of the electric force that the
  particles exert on each other.
• Answer 2

5
Electric Force

• 9.6 x 10-8N

6
Electric Force

• Two conducting spheres are placed with their
  centers exactly .50m apart. The first sphere has
  a charge of 6x10-9 C and the second one is given
  a charge of -14x10-9 C. Find the force exerted
  by one sphere on the other.
• Answer 3

7
Electric Force

• 3.024x10-6 N attraction

8
Electric Force

• 6.3 nanoC charge is placed 12 cm from a 4 nanoC
  charge. What is the electric force from one
  charge on the other?
• Answer 4

9
Electric Force

• 1.575 times 10 to the negative 5 Newtons

10
Electric Force

• Three charges lie along the x axis and the
  positive charge q1 10 nC is at 4 m and the
  positive charge q2 5 nC is at the origin. Where
  must a negative charge q3 be placed on the x axis
  so that the resultant force on it is zero?
• Answer 5

11
Electric Force

• 2.56 m

12
Uniform E Field

• Two parallel plates form an electric
  field.  Voltage between the plates is 13V and the
  distance is .25m, what is the strength of the
  field?   
• Answer 1

13
Uniform E Field

• Since the potential difference is equal to the
  negative product of the field strength and the
  distance, dividing the voltage by the distance
  yields the field strength in (V/C).

14
Uniform E Field

• A proton is released from rest in a uniform
  electric field of magnitude 12x104 V/m directed
  along the positive x axis. The proton undergoes a
  displacement of 2 meters in the direction of the
  field. What is the change in electric potential
  of the proton as a result of this displacement?
• Answer 2

15
Uniform E Field

• 2.4 x105

16
Uniform E Field

• What are some parallels between gravitational
  fields and uniform electric fields?
• Answer 3

17
Uniform E Field

• Both fields follow an inverse square law for
  force and field strength. For both types of
  field, potential energy is inversely proportional
  to distance. Also, the major difference is that
  repulsions occur in electrostatic fields between
  charges of the same sign whereas, gravity is
  always attractive.

18
Uniform E Field

• A uniform electric field of magnitude 350V/m is
  directed in the positive x direction. A positive
  13-µC moves from the origin (0, 0) to the point
  (.3m, .6m). What is the change in the potential
  energy of this charge?
• Answer 4

19
Uniform E Field

• ?PE .0014

20
Uniform E Field

• A uniform electric field of magnitude 350V/m is
  directed in the positive x direction. A positive
  13-µC moves from the origin (0, 0) to the point
  (.3m, .6m). Through what potential difference
  does it move?
• Answer 5

21
Uniform E Field

• ?V 105V

22
Point Charge E Field

• What is the electric field .4 meters away from an
  object with the charge of 5 nano Coulombs.
• Answer 1

23
Point Charge E Field

• E 281.25 N/C

24
Point Charge E Field

• True or False The direction of an electric field
  is the direction that a small negative test
  charge would travel when placed in the field.
• Answer 2

25
Point Charge E Field

• False. The direction of an electric field is the
  direction that a small positive test charge would
  travel when placed in it.

26
Point Charge E Field

• A test charge of 5 nC at a point R where the
  electric field due to other charges is directed
  to the right has a magnitude of 6x109. If the
  test charge is replaced with a charge of 5 nC
  what happens to the electric field at R?
• Answer 3

27
Point Charge E Field

• It remains the same.

28
Point Charge E Field

• What happens when a negative charge moves in the
  direction opposite the electric field?
• Answer 4

29
Point Charge E Field

• The direction of the electric field at a point is
  also defined to be the direction of the electric
  force that would be exerted on a small positive
  test charge placed at that point. Thus, it loses
  electrical potential energy since a negative
  charge released from rest in the electric field
  would accelerate in a direction opposite the
  field.

30
Point Charge E Field

• Three charges (3 nC, 4 nC, -7 nC) and a point
  charge are the four corners of a square. Each
  side of the square is 2 m. Find the electric
  field and voltage at point p.
• Answer 5

31
Point Charge E Field

• 10 X 1010 N/C

32
Voltage

• Give three other names for voltage.
• Answer 1

33
Voltage

• potential difference, electrical potential,
  electrical potential difference

34
Voltage

• If the distance between parallel charged plates
  in a uniform electric field is doubled, what
  happens to the voltage?
• Answer 2

35
Voltage

• Voltage is also doubled.

36
Voltage

• A 6 micro coulomb point charge is at the origin
  and a point charge q2 -4 micro coulomb is on
  the x axis at (9,0)m. If the electric potential
  is taken to be zero at infinity find the total
  electric potential due to these charges at point
  R with coordinates (0,12)m
• Answer 3

37
Voltage

• 2.1 x10 3 V

38
Voltage

• What is the electric potential at point P due to
  two charges (q1 and q2) which lie directly east
  west of each other. The charge of q1 is 6µC. The
  charge of q2 is -3µC. The charges lie 3 m
  apart. Find the total electric potential at point
  P which lies 5 m north of q1.
• Answer 4

39
Voltage

• 6158 V

40
Voltage

• What is the Superposition principle and how is it
  applied to find electrical potential due to a
  point charge
• Answer 5

41
Voltage

• The voltage of two or more charges is obtained by
  applying the Superposition principle which
  states that the total electric potential at some
  point due to several point charges is the
  algebraic sum of the electric potentials due to
  the individual charges.

42
Potpourri

• Define grounding and give an example.
• Answer 1

43
Potpourri

• Allowing a polarized object to become charged.
  Ex. Using your hand to take electrons from a
  charged plate and putting them onto a metal plate.

44
Potpourri

• If the distance between point P and a charge is
  doubled, what happens the the electric potential
  at point P due to the charge? 
• Answer 2

45
Potpourri

• If the distance is doubled, the electric
  potential is halved.

46
Potpourri

• A spherical ring of radius F has a total charge q
  uniformly distributed around it. What is the
  magnitude of the electric field at the center of
  the ring?
• Answer 3

47
Potpourri

• zero

48
Potpourri

• A.)There are three ways to charge an object, name
  one of them. B)Explain what creates a charge.
• Answer 4

49
Potpourri

• A)Conducton, induction or polarization. B) The
  movement and imbalance of electrons

50
Potpourri

• An electron starts from rest 4cm away from the
  center of a uniformly charged sphere of radius
  1cm. If the sphere has a charge of 2x10-9 C,
  then how fast will the electron be moving when it
  reaches the surface of the sphere?
• Answer 5

51
Potpourri

• 1.45x107 m/s