Deck 27: Sources of the Magnetic Field

Question 1

In a circular loop of wire lying on a horizontal floor,the current is constant and,to a person looking downward,has a clockwise direction.The accompanying magnetic field at the center of the circle is directed

A)horizontally and to the east.
B)horizontally and to the north.
C)vertically upward.
D)parallel to the floor.
E)vertically downward.

Answer 1

vertically downward.

Question 2

At a certain instant of time a particle with charge q = 15 $\mu$ C is located at x = 2.0 m,y = 5.0 m; its velocity at that time is v = 40 m/s .If you are at the origin,what do you measure as the magnitude of the magnetic field due to this moving point charge?

A)1.9 pT
B)3.8 pT
C)2.7 pT
D)4.1 pT
E)5.9 pT

Answer 2

1.9 pT

Question 3

A wire carries an electric current straight upward.What is the direction of the magnetic field due to the current north of the wire?

A)north
B)east
C)west
D)south
E)upward

Answer 3

west

Question 4

Two current-carrying wires are perpendicular to each other.The current in one flows vertically upward and the current in the other flows horizontally toward the east.The horizontal wire is 1 m south of the vertical wire.What is the direction of the net magnetic force on the horizontal wire?

A)north
B)east
C)west
D)south
E)There is no net magnetic force on the horizontal wire.

Question 5

A point charge is moving with speed 2 $\times$ 10⁷ m/s along the x axis.At t = 0,the charge is at x = 0 m and the magnitude of the magnetic field at x = 4 m is B₀.The magnitude of the magnetic field at x = 4m when t = 0.1 $\mu$ s is

A)B₀/2
B)B₀
C)B₀/4
D)2B₀
E)4B₀

Question 6

In a simple picture of the hydrogen atom,the electron moves in circular orbits around the central proton attracted by the Coulomb force.The lowest (n = 1)energy orbit that is allowed for the electron is at a radius of 5.29 $\times$ 10^-11 m and the second (n = 2)lowest allowed orbit is at 4 times this radius.Calculate the magnetic field strength at the proton due to the orbital motion of the electron in the n = 2 state.

A)0 T
B)6.3 T
C)0.39 T
D)12.5 T
E)None of the above

Question 7

At a certain instant of time a particle with charge q = 25 $\mu$ C is located at x = 4.0 m,y = 2.0 m; its velocity at that time is v = -20 m/s .If you are at the origin,what do you measure as the magnitude of the magnetic field due to this moving point charge?

A)6.8 pT
B)1.1 pT
C)5.6 pT
D)2.2 pT
E)4.4 pT

Question 8

The magnitude of the magnetic field due to the presence of a charged body

A)varies directly with the speed of the body.
B)varies directly with the charge carried by the body.
C)varies inversely with the square of the distance between the charged body and the field point.
D)depends on the magnetic properties of the space between the charged body and the field point.
E)is described by all of these.

Question 9

The magnetic field due to the presence of a charged body

A)depends on whether the charged body is moving.
B)depends on the direction the charged body is moving in relationship to the location of the field point.
C)varies inversely with the square of the distance between the charged body and the field point.
D)depends on the magnetic properties of the space between the charged body and the field point.
E)is described by all of these.

Question 10

The Biot-Savart law is similar to Coulomb's law in that both

A)are inverse square laws.
B)include the permeability of free space.
C)deal with excess charges.
D)are not electrical in nature.
E)are described by none of the above.

Question 11

A circular loop of wire 1.0 cm in radius carries a current of 30 A.The magnetic field at the center of the loop is

A)1.9 mT
B)2.4 mT
C)3.8 mT
D)12 $\mu$ T
E)48 $\mu$ T

Question 12

At great axial distances x from a current-carrying loop the magnetic field varies as

A)x²
B)x^-3
C)x^-2
D)x³
E)x^-1

Question 13

The top diagram shows the velocity of a positively charged particle.The direction of the magnetic field due to the moving charge at r is best represented by

A)1
B)2
C)3
D)4
E)5

Question 14

A circular loop of wire 10 cm in radius carries a current of 20 A.The axial magnetic field 15 cm from the center of the loop is approximately

A)37 $\mu$ T
B)13 $\mu$ T
C)21 $\mu$ T
D)41 $\mu$ T
E)18 $\mu$ T

Question 15

A circular loop of wire of radius 6.0 cm has 30 turns and lies in the xy plane.It carries a current of 5 A in such a direction that the magnetic moment of the loop is along the x axis.The magnetic field on the x axis at x = 6.0 cm is approximately

A)19 $\mu$ T
B)0.56 mT
C)0.11 mT
D)47 $\mu$ T
E)0.88 mT

Question 16

What is the magnetic field at the center of a circular loop with a diameter of 15.0 cm that carries a current of 1.50 A?

A)zero
B)6.28 $\times$ 10^-6 T
C)1.26 $\times$ 10^-5 T
D)2.51 $\times$ 10^-5 T
E)1.68 $\times$ 10^-4 T

Question 17

In a simple picture of the hydrogen atom,the electron moves in circular orbits around the central proton attracted by the Coulomb force.The lowest (n = 1)energy orbit that is allowed for the electron is at a radius of 5.29 $\times$ 10^-11 m and the second (n = 2)lowest allowed orbit is at 4 times this radius.How many times stronger is the magnetic field strength at the proton due to the orbital motion of the electron in the n = 1 state than the n = 2 state?

A)64
B)16
C)4
D)1
E)32

Question 18

What is the direction of the magnetic field around a wire carrying a current perpendicularly into this page?

A)The field is parallel to and in the same direction as the current flow.
B)It is parallel to but directed opposite to the current flow.
C)It is counterclockwise around the wire in the plane of the page.
D)It is clockwise around the wire in the plane of the page.
E)None of these is correct.

Question 19

A 1000-turn solenoid is 50 cm long and has a radius of 2.0 cm.It carries a current of 8.0 A.What is the magnetic field inside the solenoid near its center?

A)2.0 $\times$ 10^-2 T
B)3.2 $\times$ 10^-3 T
C)4.0 $\times$ 10^-4 T
D)1.0 T
E)2.0 $\times$ 10^-4 T

Question 20

A particle with charge q = 5 $\mu$ C is moving with velocity .At t = 0,it is located at the origin.The magnetic field at at t = 0 is

A)
B)
C)
D)
E)None of these is correct.

Question 21

The two wires in a DC adapter cable are 5 mm apart and carry a current of 4 A.If the cable is 1.5 m long,calculate the force between the wires and state if this force is attractive or not.

A)9.6 $\times$ 10^-4 N,attractive
B)9.6 $\times$ 10^-7 N,attractive
C)1.1 $\times$ 10^-8 N,attractive
D)9.6 $\times$ 10^-4 N,repulsive
E)1.1 $\times$ 10^-8 N,repulsive

Question 22

Two long,parallel wires are spaced 1 m apart in air,and you have established a current of 1 A in each.The force per unit length that each wire exerts on the other is

A)4 $\pi\mu$ ₀
B)2 $\pi\mu$ ₀
C) $\mu$ ₀
D) $\mu$ ₀/4 $\pi$
E) $\mu$ ₀/2 $\pi$

Question 23

Use the following to answer the next question:
Two long parallel wires are a distance d apart and carry equal and opposite currents.Point P is distance d from each of the wires.Which diagram best represents the direction of the magnetic field at point P?

A)1
B)2
C)3
D)4
E)5

Question 24

Use the following to answer the next two questions:

-A coil of radius R = 5 cm lies inside a long solenoid which carries a current I₁ = 10 A and has 800 turns/m.The coil carries a current I₂ = 4 A and the normal of the plane of the coil is at an angle $\theta$ = 30 ^$\circ$ with the axis of the solenoid.The magnetic field produced by the solenoid at the center is ____ times greater than the magnetic field by the coil at the center.

A)100
B)200
C)1000
D)2000
E)8000

Question 25

Two straight rods 60 cm long and 2.0 mm apart in a current balance carry currents of 18 A each in opposite directions.What mass must be placed on the upper rod to balance the magnetic force of repulsion?

A)0.50 g
B)0.99 g
C)9.7 g
D)4.3 g
E)1.6 g

Question 26

The force per unit length between two current-carrying wires is expressed as where I is the current,d the separation of the wires,and l the length of each wire.A plot of force per unit length versus I² gives a straight line,the slope of which is

A) $\mu$ ₀
B)F/l
C)(2 $\pi$ d/ $\mu$ ₀)^1/2
D) $\mu$ ₀/2 $\pi$ d
E)FI²/l

Question 27

Two long,parallel wires are spaced 1 m apart in air,and you have established a current of 1 A in each.The force per unit length that each wire exerts on the other is approximately

A)2 $\times$ 10^-6 N/m
B)2 $\times$ 10^-5 N/m
C)2 $\times$ 10^-7 N/m
D)2 $\pi$ $\times$ 10^-5 N/m
E)2 $\pi$ $\times$ 10^-6 N/m

Question 28

Calculate the magnetic field at the center of a circular current loop of area 0.200 m² divided by the magnetic field at the center of a square current loop of the same inside area for the same current I value.

A)1.00
B)1.02
C)0.246
D)0.985
E)0.785

Question 29

The magnetic field at a distance of 50 cm from a long,straight wire carrying a current of 5.0 A is approximately

A)10 $\mu$ T
B)50 $\mu$ T
C)5.0 $\mu$ T
D)32 $\mu$ T
E)2.0 $\mu$ T

Question 30

When the positive current in a long wire is flowing in a direction from S to N,it creates a magnetic field below the wire that is directed

A)from E to W.
B)from N to S.
C)from NE to SW.
D)from S to N.
E)from W to E.

Question 31

Two long,straight parallel wires 9.3 cm apart carry currents of equal magnitude I.They repel each other with a force per unit length of 5.8 nN/m.The current I is approximately

A)27 mA
B)65 mA
C)43 mA
D)52 mA
E)2.7 mA

Question 32

Ampère's law is valid

A)when there is a high degree of symmetry in the geometry of the situation.
B)when there is no symmetry.
C)when the current is constant.
D)when the magnetic field is constant.
E)for all of these conditions.

Question 33

Two long,straight parallel wires 7.6 cm apart carry currents of equal magnitude I.They attract each other with a force per unit length of 4.3 nN/m.The current I is approximately

A)1.6 mA
B)40 mA
C)37 mA
D)59 mA
E)4.0 mA

Question 34

If the magnetic field at the center of a square current loop of side L = 40 cm is 2.4 $\times$ 10^-6 T calculate the current flowing around the loop.

A)11 A
B)3.4 A
C)0.85 A
D)0.21 A
E)1.7 A

Question 35

Use the following to answer the next question:

-Two long parallel wires are a distance d apart (d = 6 cm)and carry equal and opposite currents of 5 A.Point P is distance d from each of the wires.Calculate the magnitude of the magnetic field strength at point P.

A)2.9 $\times$ 10^-5 T
B)8.5 $\times$ 10^-6 T
C)3.3 $\times$ 10^-5 T
D)1.7 $\times$ 10^-5 T
E)none of the above

Question 36

A long solenoid of radius 3 cm has 1100 turns per m.If the solenoid wire carries a current of 1.5 A,then calculate the magnetic field inside the solenoid.

A)2.1 $\times$ 10^-3 T
B)1.0 $\times$ 10^-3 T
C)1.7 $\times$ 10^-4 T
D)7.0 $\times$ 10^-2 T
E)none of the above

Question 37

Two straight rods 55 cm long and 1.4 mm apart in a current balance carry current I,each in opposite directions.If a mass of 1.3 g when placed on the upper rod balances the magnetic force of repulsion between the rods,then calculate the current I.

A)160 A
B)18 A
C)13 A
D)3.6 A
E)9.0 A

Question 38

A coil of radius R = 5 cm lies inside a long solenoid which carries a current I₁ = 10 A and has 800 turns/m.The coil carries a current I₂ = 4 A and the normal of the plane of the coil is at an angle $\theta$ = 30 ^$\circ$ with the axis of the solenoid.The magnitude of the torque on the coil is

A)1.56 $\times$ 10^-4 N . m
B)2.74 $\times$ 10^-4 N . m
C)5.03 $\times$ 10^-5 N . m
D)3.16 $\times$ 10^-4 N . m
E)none of the above

Question 39

Two parallel wires carry currents I₁ and I₂ = 2I₁ in the same direction.Which of the following expressions shows the relationship of the forces on the wires?

A)F₁ = F₂
B)F₁ = 2F₂
C)2F₁ = F₂
D)F₁ = 4F₂
E)4F₁ = F₂

Question 40

Gauss's law for magnetism summarizes the fact(s)that

A)the magnetic flux through a closed surface is zero.
B)the magnetic flux is given by _SB dA.
C)the existence of magnetic monopoles has yet to be verified.
D)there is no point in space from which magnetic field lines diverge.
E)all of the above are true.

Question 41

Use the following figure to answer the next problem:

-The tightly wound toroid shown consists of 100 turns of wire,each carrying a current I = 3 A.If a = 12 cm and b = 15 cm,the magnetic field at r = 18 cm,due to the current in this toroid,is (µ₀ = 4 $\pi$ $\times$ 10^-7 N/A²)

A)333 µT
B)400 µT
C)500 µT
D)600
E)zero

Question 42

Use the following figure to answer the next problem:

-The tightly wound toroid shown consists of 100 turns of wire,each carrying a current I = 3 A.If a = 12 cm and b = 15 cm,the magnetic field at r = 13 cm,due to the current in this toroid,is (µ₀ = 4 $\pi$ $\times$ 10^-7 N/A²)

A)333 µT
B)462 µT
C)500 µT
D)600
E)zero

Question 43

A wire of radius 0.35 cm carries a current of 75 A that is uniformly distributed over its cross-sectional area.The magnetic field at a distance of 5.0 cm from the center of the wire is approximately

A)0.47 mT
B)1.5 mT
C)0.30 mT
D)0.56 mT
E)0.24 mT

Question 44

A coaxial cable consists of a solid inner cylindrical conductor of radius 2 mm and an outer cylindrical shell of inner radius 3 mm and outer radius 3.5 mm.A current of 15 A flows down the inner wire and an equal return current flows in the outer conductor.If we assume that the currents are uniform over the cross section of the conductors,then calculate the magnitude of the enclosed current for use in Ampere's Law at a radius of 3.25 mm.

A)7.2 A
B)3.8 A
C)7.8 A
D)11.2 A
E)7.5 A

Question 45

A wire of radius 0.6 cm carries a current of 10 A that is uniformly distributed over its cross section.Calculate the magnetic field strength at r = 0.3 cm divided by that at r = 0.9 cm.

A)1.0
B)0.75
C)0.50
D)2.0
E)3.0

Question 46

Which of the following statements is false?

A)When an electric field is applied to a dielectric,the resultant electric field always decreases.
B)When a magnetic field is applied to a paramagnetic material,the resultant magnetic field always increases.
C)When a magnetic field is applied to a diamagnetic material,the resultant magnetic field always decreases.
D)When a magnetic field is applied to a ferromagnetic material,the resultant magnetic field always increases.
E)A magnetic dipole can line up parallel or anti-parallel to an applied magnetic field.

Question 47

The orbital magnetic moment of an atomic electron is

A)directly proportional to its angular momentum.
B)directly proportional to the electronic charge.
C)inversely proportional to the mass of the electron.
D)quantized as a consequence of the quantization of angular momentum.
E)described by all of the above.

Question 48

A toroid has 200 turns of wire with a current of 3 A passing through the wire.The inner radius of the toroid is 3 cm and the outer radius is 5 cm.Calculate the magnetic field strength at a radius of 2 cm.

A)6.0 $\times$ 10^-3 T
B)3.0 $\times$ 10^-3 T
C)1.2 $\times$ 10^-2 T
D)4.8 $\times$ 10^-4 T
E)none of the above

Question 49

A cylindrical bar magnet of radius 0.650 cm and length 8.30 cm has a magnetic dipole moment of magnitude m = 1.40 A · m².What is the magnetic field at the center of the magnet?

A)125 mT
B)23.0 mT
C)57.0 mT
D)160 mT
E)80.0 mT

Question 50

A wire of radius 0.6 cm carries a current of 10 A that is uniformly distributed over its cross section.Calculate the magnetic field strength at r = 0.2 cm divided by that at r = 0.4 cm.

A)1.0
B)0.75
C)0.50
D)2.0
E)3.0

Question 51

A long straight wire of radius R carries a current density J = kr A/m² where k is a constant.The magnetic field for r > R is (Hint: Current enclosed .)

A) $\mu$ ₀kR³/3r
B)2 $\pi\mu$ ₀kR³/3r
C)2 $\pi\mu$ ₀kR²/r
D)2 $\pi\mu$ ₀kR/2
E)none of the above

Question 52

The electron orbiting a proton in a hydrogen atom has a speed of v = 2.19 $\times$ 10⁶ m/s.The magnetic moment of the electron when it is orbiting at the Bohr's radius (= 0.529 nm)is

A)9.27 $\times$ 10^-24 A . m²
B)1.86 $\times$ 10^-23 A . m²
C)3.71 $\times$ 10^-23 A . m²
D)2.62 $\times$ 10^-23 A . m²
E)none of these is correct.

Question 53

Use the following figure to answer the next problem:

-The tightly wound toroid shown consists of 100 turns of wire,each carrying a current I = 3 A.If a = 12 cm and b = 15 cm,the magnetic field at r = 10 cm,due to the current in this toroid,is (µ₀ = 4 $\pi$ $\times$ 10^-7 N/A²)

A)400 µT
B)500 µT
C)600 µT
D)zero
E)impossible to calculate without additional information.

Question 54

A cylindrical bar magnet of radius 1.00 cm and length 10.0 cm has a magnetic dipole moment of magnitude m = 2.00 A · m².What is the magnetization M,assuming it to be uniform in the magnet?

A)2.53 $\times$ 10⁴ A/m
B)6.37 $\times$ 10⁴ A/m
C)3.18 $\times$ 10⁴ A/m
D)1.86 $\times$ 10⁴ A/m
E)3.18 $\times$ 10² A/m

Question 55

A long cylindrical bar magnet has a magnetization M = 3000 A/m.What is the equivalent current on the curved surface of the cylinder for 5 cm length of the magnet?

A)10 A
B)15 A
C)100 A
D)150 A
E)None of these is correct.

Question 56

A wire of radius 0.35 cm carries a current of 75 A that is uniformly distributed over its cross-sectional area.The magnetic field at the surface of the wire is approximately

A)8.4 mT
B)4.3 mT
C)6.7 mT
D)2.3 mT
E)5.7 mT

Question 57

A wire of radius 0.35 cm carries a current of 75 A that is uniformly distributed over its cross-sectional area.The magnetic field 0.20 cm from the center of the wire is approximately

A)2.5 mT
B)8.8 $\mu$ T
C)3.8 mT
D)15 mT
E)2.9 $\mu$ T

Question 58

If the magnetic susceptibility of a material is positive,

A)paramagnetic effects must be greater than diamagnetic effects.
B)diamagnetic effects must be greater than paramagnetic effects.
C)diamagnetic effects must be greater than ferromagnetic effects.
D)ferromagnetic effects must be greater than paramagnetic effects.
E)paramagnetic effects must be greater than ferromagnetic effects.

Question 59

A long straight wire of radius R carries a current density J = kr A/m² where k is a constant.The magnetic field for r < R is (Hint: Current enclosed .)

A) $\mu$ ₀kr²/2
B) $\mu$ ₀kr²/3
C)2 $\pi\mu$ ₀kr
D)2 $\pi\mu$ ₀kr/2
E)none of the above

Question 60

Diamagnetic materials

A)have small negative values of magnetic susceptibility.
B)are those in which the magnetic moments of all electrons in each atom cancel.
C)experience a small induced magnetic moment when placed in an external magnetic field.
D)exhibit the property of diamagnetism independently of temperature.
E)are described by all of the above.

Question 61

A tightly wound solenoid is 15 cm long,has 350 turns,and carries a current of 3.0 A.If you ignore end effects,you will find that the value of at the center of the solenoid when there is an iron core of magnetization M = 1.4 $\times$ 10⁶ A/m is approximately

A)11 mT
B)8.8 mT
C)1.8 mT
D)7.0 mT
E)6.2 mT

Question 62

When a sample of liquid is inserted into a solenoid carrying a constant current,the magnetic field inside the solenoid decreases by 0.005%.What is the magnetic susceptibility of the liquid?

A)-5 $\times$ 10^-5
B)+5 $\times$ 10^-5
C)3.6 $\times$ 10^-5
D)-3.6 $\times$ 10^-5
E)More information is needed to answer this question.

Question 63

If m = m_B in a paramagnetic material (m_B = 9.27 $\times$ 10^-24 J/T),at what temperature is the magnetization 3% of the saturation magnetization in an applied magnetic field of 1.00 T?

A)12.8 K
B)7.46 K
C)22.4 K
D)67.2 K
E)3.73 K

Question 64

A long solenoid is wound around a silver core ( $\chi$ _m = -2.6 $\times$ 10^-5)and carries a current.If the core is removed while the current is held constant,the magnetic field inside the solenoid

A)remains constant.
B)increases by approximately 0.003%.
C)decreases by approximately 0.003%.
D)increases by approximately 0.007%.
E)decreases by approximately 0.006%.

Question 65

A long solenoid is wound around a titanium core ( $\chi$ _m = 7.06 $\times$ 10^-5)and carries a current.If the core is removed while the current is held constant,the magnetic field inside the solenoid

A)remains constant.
B)increases by approximately 0.004%.
C)decreases by approximately 0.007%.
D)increases by approximately 0.007%.
E)decreases by approximately 0.004%.

Question 66

Nickel has a density of 8.70 g/cm³ and a molecular mass of 58.7 g/mol.Its magnetic moment is 0.587 Bohr magnetons (1 Bohr magneton = 9.27 $\times$ 10^-24 A · m²).What is its saturation magnetization?

A)4.85 $\times$ 10⁹ A/m
B)8.92 $\times$ 10⁵ A/m
C)9.27 $\times$ 10^-24 A/m
D)8.92 $\times$ 10²⁸ A/m
E)4.85 $\times$ 10⁵ A/m

Question 67

If m = m_B in a paramagnetic material (m_B = 9.27 $\times$ 10^-24 J/T),at what temperature is the magnetization 2% of the saturation magnetization in an applied magnetic field of 1.50 T?

A)8.40 K
B)33.6 K
C)22.4 K
D)16.8 K
E)4.20 K

Question 68

You place a substance in an external magnetic field and find that it is attracted to the field but only to a limited degree because of thermal agitation effects which do not permit atomic dipoles to align completely with the field.You know,therefore,that this substance is

A)diamagnetic
B)paramagnetic
C)permamagnetic
D)ferromagnetic
E)antimagnetic

Question 69

A tightly wound solenoid 15 cm long has 350 turns and carries a current of 3.0 A.If you ignore end effects,you will find that the value of at the center of the solenoid when there is no core is approximately

A)88 $\mu$ T
B)4.4 mT
C)8.8 $\mu$ T
D)8.8 mT
E)6.4 mT

Question 70

If m = m_B (in a paramagnetic material)for an external magnetic field of 20 kG,what fraction of the saturation magnetization is M at 400 K?

A)5.60 $\times$ 10^-4
B)2.24 $\times$ 10^-3
C)1.12 $\times$ 10^-3
D)3.36 $\times$ 10^-3
E)4.48 $\times$ 10^-1

Question 71

A long solenoid with 15 turns per centimeter has a core of annealed iron.When the current is 1.00 A,the magnetic field inside the iron core is 2.46 T.The applied field _app is approximately

A)18.8 $\mu$ T
B)2.46 T
C)4.32 mT
D)3.87 T
E)1.88 mT

Question 72

Cobalt has a density of 8.90 g/cm³ and a molecular mass of 58.9 g/mol.Its magnetic moment is 1.69 Bohr magnetons (1 Bohr magneton = 9.27 $\times$ 10^-24 A · m²).What is its saturation magnetization?

A)1.43 $\times$ 10⁹ A/m
B)9.10 $\times$ 10⁵ A/m
C)1.43 $\times$ 10⁶ A/m
D)9.10 $\times$ 10²⁸ A/m
E)1.69 $\times$ 10⁵ A/m

Question 73

If m = m_B (in a paramagnetic material)for an external magnetic field of 6 T,what fraction of the saturation magnetization is M at 300 K?

A)8.06 $\times$ 10^-2
B)1.34 $\times$ 10^-2
C)7.46 $\times$ 10^-3
D)4.48 $\times$ 10^-3
E)4.03 $\times$ 10^-2

Question 74

A long solenoid with 15 turns per centimeter has a core of annealed iron.When the current is 1.00 A,the magnetic field inside the iron core is 2.46 T.The relative permeability K_m is approximately

A)1800
B)1310
C)7.64 $\times$ 10^-4
D)5.56 $\times$ 10^-4
E)1500

Question 75

A tightly wound solenoid is 15 cm long,has 350 turns,carries a current of 3.0 A,and has an aluminum core ( $\chi$ _m = 2.3 $\times$ 10^-5).If you ignore end effects,you will find that the value of at the center is approximately

A)11 mT
B)8.8 mT
C)1.8 mT
D)7.0 mT
E)6.2 mT

Question 76

When a sample is inserted into a solenoid carrying a constant current,the magnetic field inside the solenoid increases by 0.005%.What is the magnetic susceptibility of the sample?

A)-5 $\times$ 10^-5
B)+5 $\times$ 10^-5
C)3.6 $\times$ 10^-5
D)-3.6 $\times$ 10^-5
E)More information is needed to answer this question.

Question 77

A cylindrical bar magnet of radius 1.0 cm and length 10 cm has a magnetic dipole moment of magnitude m = 2.0 A · m².What is the magnetic field just outside one end of the magnet?

A)40 mT
B)80 mT
C)32 mT
D)65 mT
E)93 mT

Question 78

A cylindrical bar magnet of radius 0.65 cm and length 8.3 cm has a magnetic dipole moment of magnitude m = 1.4 A · m².What is the pole strength of the magnet?

A)40 A · m
B)35 A · m
C)27 A · m
D)17 A · m
E)47 A · m

Question 79

A tightly wound solenoid is 15 cm long,has 350 turns,and carries a current of 3.0 A.If you ignore end effects,you will find that the value of _app at the center of the solenoid when there is no core is approximately

A)3.6 mT
B)44 $\mu$ T
C)4.4 mT
D)88 $\mu$ T
E)8.8 mT

Question 80

A tightly wound solenoid is 15 cm long,has 350 turns,carries a current of 3.0 A,and has an aluminum core ( $\chi$ _m = 2.3 $\times$ 10^-5).If you ignore end effects,you will find that the value of the magnetization M at the center is approximately

A)16 mA/m
B)8.8 mA/m
C)1.8 mA/m
D)24 mA/m
E)6.2 mA/m