Question 1

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

Accepted Answer

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. 
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 2

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

Accepted Answer

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%. 
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 3

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?

Accepted Answer

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

Question 4

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

Accepted Answer

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. 
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 5

Some substances,when placed in a magnetic field in free space,reduce the magnitude of the magnetic induction in the space they occupy.These substances are

Accepted Answer

A) ferromagnetic 
B) not magnetic 
C) ultramagnetic 
D) paramagnetic 
E) diamagnetic 
A) ferromagnetic 
B) not magnetic 
C) ultramagnetic 
D) paramagnetic 
E) diamagnetic

Question 6

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

Accepted Answer

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

Question 7

If m = mB in a paramagnetic material (mB = 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?

Accepted Answer

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

Question 8

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 $\theta$ = 30S1U1P1$\circ$S1S1P0 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.

Accepted Answer

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

Question 9

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.

Accepted Answer

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 
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 10

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

Accepted Answer

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. 
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 11

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?

Accepted Answer

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

Question 12

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

Accepted Answer

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

Question 13

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.

Accepted Answer

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

Question 14

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 Km is approximately

Accepted Answer

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

Question 15

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   .)

Accepted Answer

A) $\mu$0kr2/2 
B) $\mu$0kr2/3 
C) 2$\pi\mu$0kr 
D) 2$\pi\mu$0kr/2 
E) none of the above 
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 16

If m = mB in a paramagnetic material (mB = 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?

Accepted Answer

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

Question 17

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?

Accepted Answer

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

Question 18

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 $\theta$ = 30S1U1P1$\circ$S1S1P0 with the axis of the solenoid.The magnitude of the torque on the coil is

Accepted Answer

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 
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 19

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?

Accepted Answer

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

Question 20

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

Accepted Answer

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

Exam 27: Sources of the Magnetic Field

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

A long solenoid is wound around a silver core ( χ\chiχ 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

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?

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

Some substances,when placed in a magnetic field in free space,reduce the magnitude of the magnetic induction in the space they occupy.These substances are

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

If m = mB in a paramagnetic material (mB = 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 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.

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

At a certain instant of time a particle with charge q = 15 μ\muμ 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?

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

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 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 Km is approximately

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 .)

If m = mB in a paramagnetic material (mB = 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 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 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 θ\thetaθ = 30 ∘\circ∘ with the axis of the solenoid.The magnitude of the torque on the coil is

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 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

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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

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?

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 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 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 .)

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 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 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 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