Section 3: Electrical Charge and Coulomb’s Law

1

• Section 3 Electrical Charge and Coulombs Law
• Find the force between charges of 10.0 µC and
  -50.0 µC located 0.20 m apart.

2

• 2. Two spheres have identical charges and are
  0.75 m apart. The force between then is 0.30 N.
  What is the magnitude of the charge on each
  sphere? (since the charges are the same use
  F (kQ2)/(d2) and solve for Q.)

3

• 3. Consider the electric force between a pair of
  charged particles a certain distance apart.
• a. If the charge of one of the particles is
  doubled, what would the force be compared to the
  original?

4

• b. If instead, the charge of both particles is
  doubled, what would the force be compared to the
  original?

5

• c. If instead, the distance between the particles
  is doubled, what would the force be compared to
  the original?

6

• d. If the distance is halved and the charges of
  both particles are doubled, what would the force
  be compared to the original?

7

• 4. The electrostatic force between two charges
  located 2 meters apart of 15 N. What will be the
  force between these charges when they are located
  1 meter apart?

8

• 5. Anthea rubs two latex balloons against her
  hair, causing the balloons to become charged
  negatively with 2.0 x 10-6 C. She holds them a
  distance of 0.70 m apart. A) What is the
  electrical force between the two balloons? B) Is
  it one of attraction or repulsion?

9

• 6. Two pieces of puffed rice become equally
  charged as the are poured out of the box into
  Kirks cereal bowl. If the force between the
  puffed rice pieces is 4 x 10-23 N when the pieces
  are 0.03 m apart, what is the charge on each of
  the pieces?

10

• 7. When sugar is poured from the box into the
  sugar bowl, the rubbing of sugar grains creates a
  static electric charge that repels the grains,
  and causes sugar to go flying out in all
  directions. If each of two sugar grains acquires
  a charge of 3.0 x 10-11 C at a separation of 8.0
  x 10-5m, with what force will they repel each
  other?

11

• 8. Two drops of hairspray repel each other with a
  force of 9.0 x 10-9 N at a distance of 0.070 cm,
  what is the charge on each of the equally charged
  drops of hairspray?

12

• 9. Bonnie is dusting the house and raises a cloud
  of dust particles as she wipes across a table.
  If two 4.0x10-14C pieces of dust exert an
  electrostatic force of 2.0 x 10-12 N on each
  other, how far apart are the dust particles at
  this time?

13

• 10. Each of two hot air balloons acquires a
  charge of 3.0 x 10-5C on its surface as it
  travels through the air. How far apart are the
  balloons if the electrostatic force between them
  is 8.1 x 10-2N?

14

• 11. (Honors only book pg 552 7) Two very small
  spheres are initially neutral and separated by a
  distance of 0.50m. Suppose that 3.0 x 1013
  electrons are removed from one sphere and placed
  on the other. (a) What is the magnitude of the
  electrostatic force that acts on each sphere? (b)
  Is the force attractive or repulsive? Why (charge
  of electron 1.60x10-19 C)

15

• 12. (Honors only book pg 5529) The force of
  repulsion that two like charges exert on each
  other is 3.5N. What will the force be if the
  distance between the charges is increased to five
  times its original value?

16

• 13. (Honors pg 55210) In a vacuum, two particles
  have charges of q1 and q2, when q1 3.5µC. They
  are separated by a distance of 0.26m, and
  particle 1 experiences an attractive force of
  3.4N. What is q2 (magnitude and sign)?

17
14. (Honors pg 55211) Three charges are fixed to
an xy coordinate system. A charge of 18µC is on
the y axis at y 3.0m. A charge of -12µC is at
the origin. Lastly, a charge of 45 µC is on the
x axis at x 3.0m. Determine the magnitude and
direction of the net electrostatic force on the
charge at x 3.0m. Specify the direction
relative to the x axis.
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30

• Section 4 Electrical Fields
• 1. Deepika pulls her wool sweater over her head,
  which charges her body as the sweater rubs
  against her cotton shirt. A) What is the
  electrical field at a location where a 1.60 x
  10-19 C piece of lint experiences a force of 3.2
  x 10-9 N as it floats near deepika? B) What will
  happen if Deepika now touches a conductor such as
  a door knob.

31

• 2. A fly accumulates 3.0 x 10-10 C of positive
  charge as it flies through the air. What is the
  magnitude and direction of the electrical field
  at a location of 2.0 cm away from the fly?

32

• 3. Mr. Patel is photocopying lab sheets for his
  first period class. A particle of toner carrying
  a charge of 4.0 x 10-9C in the copying machine
  experiences an electric field of 1.2 x 106 N/C as
  its pulled toward the paper. What is the
  electrical force acting on the toner particle?

33

• 4. As Courtney switches on the TV set to watch
  her favorite cartoon, the electron beam in the TV
  tube is steered across the screen by the field
  between two charged plates. If the electron
  experiences a force of 3.0 x 10-6 N, how large
  is the field between the deflection plates?
  (charge of electron 1.60 x 10-19)

34

• 5. Gordon, the night custodian, dusts off a
  classroom globe with a father duster, causing the
  globe to acquire a charge of -8.0 x 10-9 C. What
  is the magnitude and direction of the electric
  field at a point 0.40 m from the center of the
  charged globe?

35

• 6. (honors only) April is decorating a tree in
  her backyard with plastic eggs in preparation for
  Easter. She hangs two eggs side by side so that
  the centers are 0.40 m apart, April rubs the eggs
  to shine them up, and in doing so places a charge
  on each egg. The egg on the left acquires a
  charge of 6.0 x 10-6 C while the egg on the right
  is charged with 4.0 x 10-6 C. What is the
  electrical field at a point 0.15 m to the right
  of the egg on the left? (hint solve for E1 and
  E2 as vectors and then find the vector sum)

36

• 6. (honors only) April is decorating a tree in
  her backyard with plastic eggs in preparation for
  Easter. She hangs two eggs side by side so that
  the centers are 0.40 m apart, April rubs the eggs
  to shine them up, and in doing so places a charge
  on each egg. The egg on the left acquires a
  charge of 6.0 x 10-6 C while the egg on the right
  is charged with 4.0 x 10-6 C. What is the
  electrical field at a point 0.15 m to the right
  of the egg on the left? (hint solve for E1 and
  E2 as vectors and then find the vector sum)

37

• 6. (honors only) April is decorating a tree in
  her backyard with plastic eggs in preparation for
  Easter. She hangs two eggs side by side so that
  the centers are 0.40 m apart, April rubs the eggs
  to shine them up, and in doing so places a charge
  on each egg. The egg on the left acquires a
  charge of 6.0 x 10-6 C while the egg on the right
  is charged with 4.0 x 10-6 C. What is the
  electrical field at a point 0.15 m to the right
  of the egg on the left? (hint solve for E1 and
  E2 as vectors and then find the vector sum)

38

• 7. (honors only book problem pg 553 25) An
  electric field of 260,000 N/C points due west at
  a certain spot. What are the magnitude and
  direction of the force that acts on a charge of
  -7.0µC at this spot?

39

• 8. (honors only book problem pg 55328) Two
  charges are placed on the x axis. One charge (q1
  8.5µC) is at x1 3.0cm and the other (q2
  - 21µC) is at x2 9.0 cm. Find the net
  electric field (magnitude and direction) at (a)
  x0cm and (b) x 6.0cm.

40

• 9. (honors only book problem pg 55330) An
  electric field with a magnitude of 160 N/C exists
  at a spot that is 0.15m away from a charge. At a
  place that is 0.45m away from this charge, what
  is the electric field strength?

41

• Section 5 Voltage
• 1. Voltage is another term for ___________________
  _________ The definition is

42

• 2. If 340 J of work is done to move 1.5x103 C of
  charge from a positive plate to a negative one,
  what is the potential difference between the
  plates?

43

• 3. What work is done when 0.024 C of charge is
  raised in potential by 3.3V?

44

• 4. A 6.0V battery does 3.2 x 10-4 J of work on an
  electric charge. What is the magnitude of the
  charge?

45

• 5. A PVC pipe is charged to 4600V, and the charge
  on the pipe is 3.2 x 10-7 C. If you are shocked
  by the pipe, how much charge will be transferred
  to you?

46

• 6. An electron in Tammies old black and white TV
  is accelerated towards the screen across a
  potential difference of 22,000V. How much
  kinetic energy does the elctron lose when it
  strikes the TV screen?

47

• 7. Amir shuffles his feet across the living room
  rug, building up a charge on his body. A spark
  will jump when there is a potential difference of
  9000V between the door and the palm of Amirs
  hand. This happens when his hand is 0.3 cm from
  the door. At this point, what is the electrical
  field between Amirs hand and the door?

48

• 8. James recharges his dead 12.0V car battery by
  sending 28,000C of charge through the terminals.
  How much electrical npotential energy must James
  store in the car battery to make it fully charged?

49

• 9. If an electron loses 1.4 x 10-15 J of energy
  in traveling from the cathode to the screen of
  Jefferys old computer, across what potential
  difference must it travel?

50

• 10. A bug zapper kills bugs that inadvertently
  stray between charged plates of the device. The
  bug causes sudden dielectric breakdown of the air
  between the plates. If two plates in a bug
  zapper are separated by 5.0 cm and the field
  between them is a uniform 2.8 x 106 V/m, what is
  the potential difference that kills the
  unsuspecting bugs?

51

• 11. While getting out of a car, Victor builds up
  a charge on his body as he slides across the
  cloth car seats. When he attempts to shut the
  car door, his hand discrarges 12,000 V through a
  uniform electric field of 3.0 x 106 V/m. How far
  is his hand from the door at the time the spark
  jumps?

52

• 12. A ligntning bolt from a cloud hits a tree
  after traveling 200m to the ground through an
  electric field of 2.0 x 106V/m. A)What is the
  potential difference between the cloud an the
  tree before the lightning bolt strikes? B)If you
  are in an open field during a lightning storm and
  the only thing you see nearby is a tall tree, is
  it a good idea to stand under the tree for
  protection from the lightning? Why or why not?