Physics 1310 chapter 18

Which one of the following best explains why tiny bits of paper are attracted to a charged rubber rod?

A) pepper is naturally a positive material

B) Paper is naturally a negative material

C) the paper becomes electrically polarized by induction

D) rubber and paper always attract each other

E) the paper acquires a net positive charge by induction

C) the paper becomes electrically polarized by induction

Five styrofoam balls are suspended from insulating threads. Several experiments are performed on the balls; and the following observations are made:

I. Ball A attracts B and A repels C.

II. Ball D attracts B and D has no effect on E.

III. A negatively charged rod attracts both A and E.

What are the charges, if any, on each ball?

A) + n + 0 +

B) + n + + 0

C) + n + 0 0

D) n + n 0 0

E) + 0 n + 0

C) + n + 0 0

Two uncharged metal spheres, A and B are suspended from insulating threads. A negatively charged rod is held near to A but not touching it, as shown. Someone moves sphere B away from A. How are the two spheres charged?

A) 0 +

B) n +

C) 0 0

D) n 0

E) + n

E) + n

Each of three objects has a net charge. Objects A and B attract one another. Objects B and C also attract one another, but objects A and C repel one another. Which one of the following table entries is a possible combination of the signs of the charges on these three objects?

A) + + n

B) n + +

C) + n n

D) n + n

E) n n +

D) n + n

A conducting sphere has a charge of n6.4 x10^n17 C. What is the approximate number of excess electrons on the sphere?

A) 100

B) 200

C) 300

D) 400

E) 500

D) 400

Complete the following statement: When an ebonite rod is rubbed with animal fur, the rod becomes negatively charged as

A) positive charges are transferred from the fur to the rod

B) negative charges are transferred from the rod to the fur

C) negative charges are created on the surface of the rod

D) negative charges are transferred from the fur to the rod

E) positive charges are transferred from the rod to the fur

D) negative charges are transferred from the fur to the rod

Complete the following statement: when a glass rod is rubbed with a silk cloth, the rod becomes positively charged as

A) positive charges are transferred from the silk to the rod

B) negative charges are transferred from the rod to the silk

C) negative charges are created on the surface of the rod

D) negative charges are transferred from the silk to the rod

E) positive charges are transferred from the rod to the silk

B) negative charges are transferred from the rod to the silk

A charged conductor is brought near an unchanged insulator. Which of the following statements is true?

A) both objects will attract each other

B) both objects will attract each other

C) neither object exerts an electrical force on the other

D) the objects will repel each other only if the conductor has a negative charge

E) the objects will attract each other only if the conductor has a positive charge

B) both objects will attract each other

An aluminum nail has an excess charge of +3.2 µC. How many electrons must be added to the nail to make it electrically neutral?

A) 2.0 x10^13

B) 2.0 x10^ 19

C) 3.2 x10^16

D) 3.2 x10^6

E) 5.0 x10 ^n14

A) 2.0 x10^13

Two uncharged, conducting spheres, A and B, are held at rest on insulating stands and are in contact. A positively charged rod is brought near sphere A as suggested in the figure. While the rod is in place, someone moves sphere B away from A. How will the spheres be charged, if at all?

A) + +

B) + -

C) - +

D) - -

E) 0 0

C) - +

Consider the identical metal spheres A, B and C. Sphere A carries a charge of n6.0 µC. Sphere A and B are touched together and then separated. Does sphere C end up with an excess or a deficiency of electrons and how many electrons is it?

A) deficiency 6x10 ^13

B) excess 3x10 ^13

C) excess 2x10^13

D) deficiency 3x10 ^12

E) there is no deficiency or excess of electrons

E) there is no deficiency or excess of electrons

Two charged particles A and B are located near one another. Both the magnitude and direction of the force that particle A exerts on Particle B is independent of

A) the sign of charge B

B) the sign of charge A

C) the distance between A and B

D) the magnitude of the charge on B

E) the magnitude and and direction are dependent on all of the above

E) the magnitude and and direction are dependent on all of the above

* see picture question 13

Four point charges of equal magnitude but with varying signs are arranged on the corners of a square as shown. Which arrow labelled A, B, C, D represents the net force acting on the center charge?

A) A

B) B

C) C

D) D

E) the net force on that charge is zero

B) B

Two positive point charges Q and 2Q are separated by a distance R. If the charge Q experiences a force of magnitude F when the separation is R, what is the magnitude of the force on the charge 2Q when the separation is 2R ?

A) F/4

B) F/2

C) F

D) 2F

E) 4F

A) F/4

A charge Q exerts a 1.2 N force on another charge q. If the distance between the charges is doubled, what is the magnitude of the force exerted on Q by q?

A) 0.30 N

B) 0.60 N

C) 2.4 N

D) 3.6 N

E ) 4.8 N

A) 0.30 N

At what separation will two charges each of magnitude 6.0µC, exert a force of 0.70 N on each other?

A) 1.1 x10 ^n5 m

B) 0.23 m

C) 0.48 m

D) 0.68 m

E) 1.4 m

D) 0.68 m

One mole of a substance contains 6.0 x10^23 protons and an equal number of electrons. If the protons could somehow be separated from the electrons and placed in ver small individual containers separated by a million meters, what would be the magnitude of the electrostatic force exerted by one box on the other?

A) 8.7 x10^3 N

B) 9.5 x10^4 N

C) 2.2 x10 ^5 N

D) 8.4 x 10 ^7 N

E) 1.6 x 10^8 N

D) 8.4 x 10 ^7 N

* see picture, question 18

Three charges are positioned as indicated in the figure. What are the horizontal and vertical components of the net force exerted on the +15 µC charge by the +11 µC and +13 µC charges?

A) 95 N 310 N

B) 76 N 310 N

C) 250 N 130 N

D) 95 N 130 N

E) 76 N 370 N

E) 76 N 370 N

A ñ4.0 µC charge is located 0.45m to the left of a +6.0 µC charge. What is the magnitude of the electrostatic force on the positive charge?

A) 2.2 N to the right

B) 2.2 N to the left

C) 1.1 N to the right

D) 1.1 N to the left

E) 4.4 N to the right

D) 1.1 N to the left

Determine the ratio of the electrostatic force to the gravitational force between the a proton and an electron FE/ FG

A) 1.24 x10^23

B) 2.52 x10^29

C) 1.15 x10^31

D) 2.26 x10^39

E) 1.42 x10^58

D) 2.26 x10^39

*Look at image on question 21

In Frame 1, two identical conducting spheres, A and B, carry equal amounts of excess charge that have the same sign. The spheres are separated by a distance d; and sphere A exerts an electrostatic force on sphere B that has a magnitude F. A third sphere, C, which is handled only by an insulating rod, is introduced in Frame 2. Sphere C is identical to A and B except that it is initially uncharged. Sphere C is touched first to sphere A, in Frame 2, and then to sphere B, in Frame 3, and is finally removed in Frame 4.

Determine the magnitude of the electrostatic force that sphere A exerts on sphere B in Frame 4.

A) F/2

B) F/3

C) 3F/4

D) 3F/8

E) zero

D) 3F/8

*Look at image question 22

Three identical point charges, Q are placed at the vertices of an equilateral triangle as shown in figure. The length if each side of triangle is D. Determine magnitude and direction of the total electrostatic force on the charge at the top of the triangle.

A) upward

B) downward

C) zero

A) upward

*Look at image question 23

Three charges are located along the x axis as shown in the drawing. The mass of the ñ 1.2 µC is 4.0 x10^n9 kg.

Determine the magnitude and direction of the acceleration of the ñ1.2 µC charge when it is allowed to move if the other two charges remain fixed.

A) 2 x10^5 m/s^2

B) 1 x10^5 m/s^2

C) 7 x10^4 m/s^2

D) 3 x10^5 m/s^2

E) 4 x10^6 m/s^2

B) 1 x10^5 m/s^2

Look at image question 24

Four point charges are held fixed at corners of square as shown in image. Which of following 5 arrows shown below most accurately shows the direction of the net force on charge nQ due to presence of the three other charges?

A) 45 degrees below x axis

B) left

C) less than 45 above axis

D) up

E) 45 degree angle above x axis

E) 45 degree angle above x axis

The figure-shows an equilateral triangle ABC. A positive point charge +q is located at each of the vertices A, B, C. Each side of the triangle is a length of a A pint charge Q (that may be positive or negative) is placed at the midpoint between B and C.

Is it possible to choose the value Q (that is not 0) explain why or why not?

A) yes because the forces on Q are vectors and three vectors can add to zero

B) no because the forces on Q are vectors and three vectors can never equal zero

C) yes because electric force at midpoint between B and C is zero whether a charge has placed or not

D) no because the forces on Q due to the charges at B and C point in the same direction

E) no because the fourth charge would be needed to cancel the force on Q due to the charge at A

E) no because the fourth charge would be needed to cancel the force on Q due to the charge at A

Which of the following statements is true concerning the magnitude of the electric field at a point in space?

A) it is a measure of the total charge of the object

B) it is a measure of the electric force on any charged object

C) it is a measure of the ratio of the charge on an object to its mass

D) it is a measure of the electric force per unit mass on a test charge

E) it is a measure of the electric force per unit charge on a test charge

E) it is a measure of the electric force per unit charge on a test charge

Look at image, question 28

In the figure, point A is a distance L away from a pony charge Q. Point B is a distance 4L away from Q. What is the ratio of the electric field at B to that at A. EB/EA

A) 1/16

B) 1/9

C) 1/4

D) 1/3

E) this cannot be determined since neither value of Q nor the length L is specified

A) 1/16

Look at image question 29

At which point(s) is the electric field zero N/C for the two point charges shown on the x- axis?

A) the electric field is never zero in the vicinity of these charges

B) the electric field is zero somewhere on x axis to the left of the +4q charge

C) the electric field is. Euro somewhere on the x axis to the right of the ñ2q charge

D) the electric field is zero somewhere on the x axis between the two charges, but this point is nearer to the ñ2q charge

E) the electric field is zero at two points along the x axis, one such pond is to the right of the ñ2q charge and the other is to the left of the +4q charge

C) the electric field is. Euro somewhere on the x axis to the right of the ñ2q charge

An electron is travelling horizontally enters a region where a uniform electric field is directed upward. What is the direction of the force exerted on the electron once it has entered the field?

A) left

B) right

C) up

D) down

E) out of page

D) down

Which of the following statements is true concerning the strength of the electric field between the two oppositely charged parallel plates?

A) it is zero midway between the plates

B) it is a maximum midway between the plates

C) it is a maximum near the positively charged plate

D) it is a maximum near the negatively charged plate

E) it is a constant between the plates except near the edges

E) it is a constant between the plates except near the edges

Two particles of the same mass carry charges +3Q and -2Q, respectively. They are shot into a region that contains a uniform electric field as shown. The particles have the same initial velocities in the positive x direction. The lines, numbered 1 through 5, indicate possible paths for the particles. If the electric field points in the negative y direction, what will be the resulting paths for these particles?

A) path 1 for +3Q and path 4 for ñ2Q

B) path 3 for +3Q and path 2 for ñ2Q

C) path 4 for +3Q and path 3 for ñ2Q

D) path 2 for +3Q and path 5 for ñ2Q

E) path 5 for +3Q and path 2 for ñ2Q

E) path 5 for +3Q and path 2 for ñ2Q

Five particles are shot from the left into a region that contains a uniform electric field. The numbered lines show the paths taken by the five particles. A negatively charged particle with a charge -3Q follows path 2 while it moves through this field. Do not consider any effects due to gravity.

In which direction does the electric field point?

A) toward top of page

B) toward left of page

C) toward right of page

D) toward bottom of page

E) out of page

D) toward bottom of page

Five particles are shot from the left into a region that contains a uniform electric field. The numbered lines show the paths taken by the five particles. A negatively charged particle with a charge -3Q follows path 2 while it moves through this field. Do not consider any effects due to gravity.

Which path would be followed by a helium atom ( an electrically neutral particle?

A) path 1

B) path 2

C) path 3

D) path 4

E) path 5

C) path 3

Five particles are shot from the left into a region that contains a uniform electric field. The numbered lines show the paths taken by the five particles. A negatively charged particle with a charge -3Q follows path 2 while it moves through this field. Do not consider any effects due to gravity.

Which path would be followed by a charge if +6Q?

A) path 1

B) path 2

C) path 3

D) path 4

E) path 5

E) path 5

What is the magnitude of the electric field due to a 6.0 x10^ñ9 C charge at a point located 0.025m from the charge?

A) 8.6 x10^2 N/C

B) 1.2 x10 ^4 N/C

C) 1.8 x10^5 N/C

D) 3.6 x10^6 N/C

E) 7.2 x10^7 N/C

A) 8.6 x10^2 N/C

The figure shows a parallel plate capacitor. The surface charge density on each plate is 8.8 x10^ñ8 C/m^2. The point P is located 1.0 x10^ ñ5 m away from the positive plate.

Which of the following statements concerning the direction of the electric field between the plates is true?

A) points to left

B) points to right

C) points to negative plate

D) points to positive plate

E) points up out of plane of page

C) points to negative plate

The figure shows a parallel plate capacitor. The surface charge density on each plate is 8.8 x10^ñ8 C/m^2. The point P is located 1.0 x10^ ñ5 m away from the positive plate.

What is the magnitude of the electric field at the point P?

A) 8.8 N/C

B) 88N/C

C) 1.0 x10^2 N/C

D) 8.8 x10^2 N/C

E) 9.9 x10^3 N/ C

E) 9.9 x10^3 N/ C

If a +2.0 × 10-5 C point charge is placed at P, what is the force exerted on it?

A) 0.2 N, toward the negative plate

B) 0.2 N, toward the positive plate

C) 5 × 104 N, toward the positive plate

D) 5 × 104 N, toward the negative plate

E) 5 × 104 N, into the plane of the page

A) 0.2 N, toward the negative plate

A small sphere of mass 2.5 × 10-5 kg carries a total charge of 6.0 × 10-8 C. The sphere hangs from a silk thread between two large parallel conducting plates. The excess charge on each plate is equal in magnitude, but opposite in sign. If the thread makes an angle of 30° with the positive plate as shown, what is the magnitude of the charge density on each plate?

A) 2.5 x10ñ9 C/ m^2

B) 5.2 x10ñ9 C/ m^2

C) 1.0 x10ñ9 C/ m^2

D) 2.1 x10ñ8 C/ m^2

E) 4.2 x10ñ8 C/ m^2

D) 2.1 x10ñ8 C/ m^2

Complete the following statement: the magnitude of the electric field at a point in space does not depend upon

A) the distance from the charge causing the field

B) the sign of the charge causing the field

C) the magnitude of the charge causing the field

D) the force that a unit positive charge will experience at the point

E) the force that a unit negative charge will experience at that point

B) the sign of the charge causing the field

Four point charges are placed on corners of a square as shown in the figure. Each side of the squares has length 2.0m. Determine the magnitude of the electric field at point P, the centre of the square.

A) 2.0 x10ñ6 N/ C

B) 3.0 x10ñ6 N/C

C) 9.0 x10^3N/C

D) 1.8 x10^4 N/C

E) 2.7 x 10^4 N/C

D) 1.8 x10^4 N/C

The figure shows the electric field lines in the vicinity of two point charges. Which one of the following statements concerning this situation is true?

A. q1 is negative and q2 is positive.

B. The magnitude of the ratio (q2/ q1) is 0.70.

C. Both q1and q2 have the same sign of charge.

D. The magnitude of the electric field is the same everywhere.

E. The electric field is strongest midway between the charges.

B) The magnitude of the ratio (q2/ q1) is 0.70.

A rigid electric dipole is free to move in the electric field represented in the figure. Which one of the following phrases most accurately describes the initial motion of the dipole if it is released from rest in the position shown?

A) It moves to the left.

B) It moves to the right.

C) It does not move at all.

D) It moves toward to the top of the page.

E) It moves toward the bottom of the page.

A) it moves to the left

An electric dipole is released from rest in a uniform electric field with the orientation shown. Which entry in the table below correctly describes the net torque and the net force of the dipole?

A) zero zero

B) clockwise zero

C) counterclockwise zero

D) clockwise Non-zero

E) counterclockwise Non- zero

D) clockwise non-zero

Which One Of The Following Statements Is True Concerning The Spacing Of The Electric Field Lines In The Vicinity Of Two Point Charges Of Equal Magnitude And Opposite Sign?

A) The spacing is large when the magnitude of the charges is large.

B. The spacing is small when the magnitude of the charges is small.

C. The spacing does not depend on the magnitude of the charges.

D. The spacing indicates the direction of the electric field.

E. The spacing indicates the relative magnitude of the electric field.

D) The spacing indicates the direction of the electric field.

Which one of the following statements is true concerning the electrostatic charge on a conductor?

A. It is uniformly distributed throughout the volume

B. It is confined to the surface and is uniformly distributed

C. Most of the charge is on the outer surface, but it is not uniformly distributed

D. It is entirely on the surface and it is distributed according to the shape of the object

E. It is dispersed throughout the volume of the object and distributed according to the object's shape

D) It is entirely on the surface and it is distributed according to the shape of the object

The magnitude of the electric field at a distance of two meters from a negative point charge is E. What is the magnitude of the electric field at the same location if the magnitude of the charge is doubled.

A) E/4

B) E/2

C) E

D) 2E

E) 4E

D) 2E

What is the magnitude and direction of the electric force on a ñ3.0 uC charge at a point where the electric field is 2800 N/C and is directed along the +y-axis?

A) 0.018 N ñy direction

B) 0.012 N +y direction

C) 0.0084 N ñy direction

D) 0.0056 N +y direction

E) 0.022N +x direction

C) 0.0084 N ñy direction

A conducting sphere carries a net charge of +6 µC. The sphere is located at the center of a conducting spherical shell that carries a net charge of ñ2 µC. Determine the excess charge on the outer surface of the spherical shell.

A) ñ4 uC

B) +4 uC

C) ñ8 uC

D) +8 uC

E) +6 uC

B) +4 uC

A cubical Gaussian surface is placed in a uniform electric field as shown in the figure. The length of each edge of the cube is 1.0 m. The uniform electric field has a magnitude of 5.0 × 108 N/C and passes through the left and right sides of the cube perpendicular to the surface. What is the total electric flux that passes through the cubical Gaussian surface?

A) 5.0 × 108 N⋅m2/C

B) 3.0 × 109 N⋅m2/C

C) 2.5 × 106 N⋅m2/C

D) 1.5 × 107 N⋅m2/C

E) zero N⋅m2/C

E) zero N⋅m2/C

What is the electric flux passing through a Gaussian surface that surrounds a +0.075 C point charge?

A) 8.5 x10^9Nm^2/C

B)6.8 x10^8 Nm^2/C

C) 1.3 x10^7 Nm^2/C

D) 4.9 x10^6 Nm^2 /C

E) 7.2 x10^5 Nm^2/C

B) 8.5 x10^9Nm^2/C

A uniform electric field with a magnitude of 125,000 N/C passes through a rectangle with sides of 2.50 m and 5.00 m. The angle between the electric field vector and the vector normal to the rectangular plane is 65.0 degrees. What is the electric flux through the rectangle?

A) 1.56 x10^6 Nm^2C

B) 6.60 x10^5 Nm^2/C

C) 1.42 x10^5 Nm^2 /C

D) 5.49 x10^4 Nm^2/C

E) 4.23 x10^4 Nm^2/C

B) 6.60 x10^5 Nm^2/C

A straight, copper wire has a length of 0.50 m and an excess charge of ñ1.0 × 10^5 C distributed uniformly along its length. Find the magnitude of the electric field at a point located 7.5 × 10^3 m from the midpoint of the wire.

A) 1.9 x10^10 N/ C

B) 1.5 x10^6 N/C

C) 6.1 x10^13 N/ C

D) 7.3 x10^8 N/C

E) 4.8 x10^7 N/C

E) 4.8 x10^7 N/C

A total charge of ñ6.50mC is uniformly distributed within a sphere that has a radius of 0.150 m. What is the magnitude and direction of the electric field at 0.300m from the surface of the sphere?

A) 2.89 x10^5 N/C radically inward

B) 6.49 x10^5 N/C radically outward

C) 4.69 x10^5 N/C radically inward

D) 9.38 x10^5 N/C radically outward

E) 1.30 x10^6 N/C radically inward

A) 2.89 x10^5 N/C radically inward

A circular loop of wire with a diameter of 0.626 m is rotated in a uniform electric field to a position where the electric flux through the loop is a maximum. At this position, the electric flux is 7.50 x 105 N×m2/C. Determine the magnitude of the electric field.

A) 8.88 × 105 N/C

B) 1.07 × 106 N/C

C) 2.44 × 106 N/C

D) 4.24 × 106 N/C

E) 6.00 × 106 N/C

C) 2.44 × 106 N/C

A helium nucleus is located between the plates of a parallel- plate capacitor as shown. The nucleus has a charge of +2E and a mass of 6.6 x10^ñ27 kg. What is the magnitude of the electric field such that the electric force exactly balances the weight of the helium nucleus so that it remains stationary?

A) 4.0 x10 ñ7 N/ C

B) 6.6 x10 ñ26 N/C

C) 2.0 x10 ñ7 N/C

D) 5.0 x10 ñ3 N/ C

E) 1.4 x10^ñ8 N/C

C) 2.0 x10 ñ7 N/C

Two identical conducting spheres carry charges of +5.0 μC and -1.0 μC, respectively. The centers of the spheres are initially separated by a distance L. The two spheres are brought together so that they are in contact. The spheres are then returned to their original separation L. What is the ratio of the magnitude of the electric force on either sphere after the spheres are touched to that before they were touched?

A) 1/1

B) 4/5

C) 9/5

D) 5/1

E) 4/9

B) 4/5

Two point charges, A and B lie along a line separated by a distance L. The point x is the midpoint of their separation.

Which combination of charges would yield the greatest repulsive force between the charges?

A) ñ2q and ñ4q

B) +1q and ñ3q

C) ñ1q and ñ4q

D) ñ2q and +4q

E) +1q and +7q

A) ñ2q and ñ4q

Which combinations of charges will yield zero electric at the point x?

A) +1q and ñ1q

B) +2q and ñ3q

C) +1q and ñ4q

D) ñ1q and +4q

E) +4q and +4q

E) +4q and +4q

A solid, conducting sphere of radius a carries an excess charge of +6 µC. This sphere is located at the center of a hollow, conducting sphere with an inner radius of b and an outer radius of c as shown. The hollow sphere also carries a total excess charge of +6 µC. Determine the excess charge on the INNER surface of the outer sphere.

A) zero coulombs

B) ñ6 uC

C) +6 uC

D) +12 uC

E) ñ12 uC

B) ñ6 uC

A solid, conducting sphere of radius a carries an excess charge of +6 µC. This sphere is located at the center of a hollow, conducting sphere with an inner radius of b and an outer radius of c as shown. The hollow sphere also carries a total excess charge of +6 µC. Determine the excess charge on the OUTER surface of the outer sphere.

A) zero coulombs

B) ñ6 uC

C) +6 uC

D) +12 uC

E) ñ12 uC

D) +12 uC

Look at image question 63

Which one of the following figures shows a qualitatively accurate sketch of the E,extricate field lines in and around this system?

C) c .... All pointing outwards