Question 1

A particle with charge -5.00 C initially moves at   = (1.00   + 7.00   )m/s.If it encounters a magnetic field   find the magnetic force vector on the particle.

Accepted Answer

A)  (-350   + 50.0   ) N 
B)  (-350   - 50.0   ) N 
C)  (350   + 50.0   ) N 
D)  (350   - 50.0   ) N 
A)  (-350   + 50.0   ) N 
B)  (-350   - 50.0   ) N 
C)  (350   + 50.0   ) N 
D)  (350   - 50.0   ) N

Question 2

A proton,with mass 1.67 × 10-27 kg and charge +1.6 × 10-19 C,is sent with velocity   in the +x direction into a region where there is a uniform electric field of magnitude 730 V/m in the +y direction.What are the magnitude and direction of the uniform magnetic field in the region,if the proton is to pass through undeflected? Assume that the magnetic field has no x-component and neglect gravitational effects.

Accepted Answer

0.010 T,+z

Question 3

A 15-turn rectangular loop of wire of width 10 cm and length 20 cm has a current of 2.5 A flowing through it.Two sides of the loop are oriented parallel to a uniform magnetic field of strength 0.037 T,and the other two sides are perpendicular to the magnetic field.
(a)What is the magnitude of the magnetic moment of the loop?
(b)What torque does the magnetic field exert on the loop?

Accepted Answer

(a)0.75 A

Question 4

A wire along the z-axis carries a current of 6.8 A in the +z direction.Find the magnitude and direction of the force exerted on a 6.1-cm long length of the wire by a uniform magnetic field with magnitude 0.36 T in the -x direction.

Accepted Answer

The answer of A wire along the z-axis carries a...

Question 5

A thin copper rod that is 1.0 m long and has a mass of 0.050 kg is in a magnetic field of 0.10 T.What minimum current in the rod is needed in order for the magnetic force to cancel the weight of the rod?

Accepted Answer

A)  1.2 A 
B)  2.5 A 
C)  4.9 A 
D)  7.6 A 
E)  9.8 A 
A)  1.2 A 
B)  2.5 A 
C)  4.9 A 
D)  7.6 A 
E)  9.8 A

Question 6

A doubly charged ion (charge 2e)with velocity 6.9 × 106 m/s moves in a circular path of diameter 60.0 cm in a magnetic field of 0.80 T in a mass spectrometer.What is the mass of this ion? (e = 1.60 × 10-19C)

Accepted Answer

A)  11 × 10-27 kg 
B)  6.7 × 10-27 kg 
C)  4.5 × 10-27 kg 
D)  3.3 × 10-27 kg 
E)  8.2 × 10--27 kg 
A)  11 × 10-27 kg 
B)  6.7 × 10-27 kg 
C)  4.5 × 10-27 kg 
D)  3.3 × 10-27 kg 
E)  8.2 × 10--27 kg

Question 7

A wire carries a 4.0-A current along the +x-axis through a magnetic field   .If the wire experiences a force of 30 N   as a result,how long is the wire?

Accepted Answer

A)  1.1 m 
B)  0.87 m 
C)  1.5 m 
D)  0.63 m 
A)  1.1 m 
B)  0.87 m 
C)  1.5 m 
D)  0.63 m

Question 8

A charge is accelerated from rest through a potential difference V and then enters a uniform magnetic field oriented perpendicular to its path.The field deflects the particle into a circular arc of radius R.If the accelerating potential is tripled to 3V,what will be the radius of the circular arc?

Accepted Answer

A)  9R 
B)  3R 
C)    R 
D)  R/   
E)  R/9 
A)  9R 
B)  3R 
C)    R 
D)  R/   
E)  R/9

Question 9

A straight wire that is 0.60 m long is carrying a current of 2.0 A.It is placed in a uniform magnetic field of strength 0.30 T.If the wire experiences a force of 0.18 N,what angle does the wire make with respect to the magnetic field?

Accepted Answer

A)  25° 
B)  30° 
C)  35° 
D)  60° 
E)  90° 
A)  25° 
B)  30° 
C)  35° 
D)  60° 
E)  90°

Question 10

A rectangular loop of wire carrying a 4.0-A current is placed in a magnetic field of 0.60 T.The magnitude of the torque acting on this wire when the plane of the loop makes a 30° angle with the field is measured to be 1.1 N • m.What is the area of this loop?

Accepted Answer

A)  0.20 m2 
B)  0.40 m2 
C)  0.26 m2 
D)  0.80 m2 
E)  0.53 m2 
A)  0.20 m2 
B)  0.40 m2 
C)  0.26 m2 
D)  0.80 m2 
E)  0.53 m2

Question 11

An electron moving perpendicular to a uniform magnetic field of 3.2 × 10-2 T moves in a circle of radius 0.40 cm.How fast is this electron moving? (mel = 9.11 × 10-31 kg,

Accepted Answer

A)  2.2 × 107 m/s 
B)  1.9 × 10-2 m/s 
C)  1.9 × 10-30 m/s 
D)  3.0 × 106 m/s 
E)  8.0 × 106 m/s 
A)  2.2 × 107 m/s 
B)  1.9 × 10-2 m/s 
C)  1.9 × 10-30 m/s 
D)  3.0 × 106 m/s 
E)  8.0 × 106 m/s

Question 12

A uniform magnetic field of magnitude 0.80 T in the negative z-direction is present in a region of space,as shown in the figure.A uniform electric field is also present.An electron that is projected with an initial velocity   in the positive x-direction passes through the region without deflection.What is the electric field vector in the region?

Accepted Answer

A)  -73 kV/m   
B)  +73 kV/m   
C)  +110 kV/m   
D)  +110 kV/m   
E)  -110 kV/m   
A)  -73 kV/m   
B)  +73 kV/m   
C)  +110 kV/m   
D)  +110 kV/m   
E)  -110 kV/m

Question 13

An electron,moving toward the west,enters a uniform magnetic field.Because of this field the electron curves upward.The direction of the magnetic field is

Accepted Answer

A)  towards the north. 
B)  towards the south. 
C)  towards the west. 
D)  upward. 
E)  downward. 
A)  towards the north. 
B)  towards the south. 
C)  towards the west. 
D)  upward. 
E)  downward.

Question 14

A rigid circular loop has a radius of 0.20 m and is in the xy-plane.A clockwise current I is carried by the loop,as shown.The magnitude of the magnetic moment of the loop is   A uniform external magnetic field,B = 0.20 T in the positive x-direction,is present.   (a)What is the current in the loop?
(b)Find the magnitude of the magnetic torque exerted on the loop.
(c)If the loop is released from rest,in what direction will points a and c initially move?

Accepted Answer

(a)6.0 A (b)0.15 N ∙

Question 15

A charged particle is moving with speed v perpendicular to a uniform magnetic field.A second identical charged particle is moving with speed 2v perpendicular to the same magnetic field.If the frequency of revolution of the first particle is f,the frequency of revolution of the second particle is

Accepted Answer

A)  f. 
B)  2f. 
C)  4f. 
D)  f/2. 
E)  f/4. 
A)  f. 
B)  2f. 
C)  4f. 
D)  f/2. 
E)  f/4.

Question 16

In a mass spectrometer,a singly-charged particle (charge e)has a speed of 1.0 × 106 m/s and enters a uniform magnetic field of 0.20 T.The radius of the circular orbit of the particle is 0.020 m.What is the mass of this particle? (e = 1.60 × 10-19C)

Accepted Answer

A)  3.2 × 10-28 kg 
B)  6.4 × 10-28 kg 
C)  1.7 × 10-27 kg 
D)  4.5 × 10-27 kg 
E)  3.1 × 10--31 kg 
A)  3.2 × 10-28 kg 
B)  6.4 × 10-28 kg 
C)  1.7 × 10-27 kg 
D)  4.5 × 10-27 kg 
E)  3.1 × 10--31 kg

Question 17

An alpha particle is moving at a speed of 5.0 × 105 m/s in a direction perpendicular to a uniform magnetic field of strength 0.040 T.The charge on an alpha particle is 3.2 × 10-19 C and its mass is 6.6 × 10-27 kg.
(a)What is the radius of the path of the alpha particle?
(b)How long does it take the alpha particle to make one complete revolution around its path?

Accepted Answer

Question 18

A rigid rectangular loop,which measures 0.30 m by 0.40 m,carries a current of 5.5 A,as shown in the figure.A uniform external magnetic field of magnitude 2.9 T in the negative x direction is present.Segment CD is in the xz-plane and forms a 35° angle with the z-axis,as shown.Find the magnitude of the external torque needed to keep the loop in static equilibrium.

Accepted Answer

A)  1.1 N • m 
B)  0.73 N • m 
C)  1.3 N • m 
D)  1.4 N • m 
E)  1.6 N • m 
A)  1.1 N • m 
B)  0.73 N • m 
C)  1.3 N • m 
D)  1.4 N • m 
E)  1.6 N • m

Question 19

A circular loop of diameter 10 cm,carrying a current of 0.20 A,is placed inside a magnetic field   = 0.30 T   .The normal to the loop is parallel to a unit vector   = -0.60   - 0.80   .Calculate the magnitude of the torque on the loop due to the magnetic field.

Accepted Answer

A)  4.7 × 10-4 N • m 
B)  2.8 × 10-4 N • m 
C)  0.60 × 10-4 N • m 
D)  1.2 × 10-4 N • m 
E)  zero 
A)  4.7 × 10-4 N • m 
B)  2.8 × 10-4 N • m 
C)  0.60 × 10-4 N • m 
D)  1.2 × 10-4 N • m 
E)  zero

Question 20

A wire segment 1.2 m long carries a current I = 3.5 A and is oriented as shown in the figure.A uniform magnetic field of magnitude 0.50 T pointing toward the -x direction is present as shown.The +z-axis points directly into the page.What is the magnetic force vector on the wire segment?

Accepted Answer

A)  +1.6 N   
B)  -1.6 N   
C)  +1.6 N   
D)  (+1.3   - 1.6   ) N 
E)  (-1.3   + 1.6   N 
A)  +1.6 N   
B)  -1.6 N   
C)  +1.6 N   
D)  (+1.3   - 1.6   ) N 
E)  (-1.3   + 1.6   N

Exam 27: Magnetic Field and Magnetic Forces

A particle with charge -5.00 C initially moves at = (1.00 + 7.00 )m/s.If it encounters a magnetic field find the magnetic force vector on the particle.

A wire along the z-axis carries a current of 6.8 A in the +z direction.Find the magnitude and direction of the force exerted on a 6.1-cm long length of the wire by a uniform magnetic field with magnitude 0.36 T in the -x direction.

A thin copper rod that is 1.0 m long and has a mass of 0.050 kg is in a magnetic field of 0.10 T.What minimum current in the rod is needed in order for the magnetic force to cancel the weight of the rod?

A doubly charged ion (charge 2e)with velocity 6.9 × 106 m/s moves in a circular path of diameter 60.0 cm in a magnetic field of 0.80 T in a mass spectrometer.What is the mass of this ion? (e = 1.60 × 10-19C)

A wire carries a 4.0-A current along the +x-axis through a magnetic field .If the wire experiences a force of 30 N as a result,how long is the wire?

A charge is accelerated from rest through a potential difference V and then enters a uniform magnetic field oriented perpendicular to its path.The field deflects the particle into a circular arc of radius R.If the accelerating potential is tripled to 3V,what will be the radius of the circular arc?

A straight wire that is 0.60 m long is carrying a current of 2.0 A.It is placed in a uniform magnetic field of strength 0.30 T.If the wire experiences a force of 0.18 N,what angle does the wire make with respect to the magnetic field?

A rectangular loop of wire carrying a 4.0-A current is placed in a magnetic field of 0.60 T.The magnitude of the torque acting on this wire when the plane of the loop makes a 30° angle with the field is measured to be 1.1 N • m.What is the area of this loop?

An electron moving perpendicular to a uniform magnetic field of 3.2 × 10-2 T moves in a circle of radius 0.40 cm.How fast is this electron moving? (mel = 9.11 × 10-31 kg,

An electron,moving toward the west,enters a uniform magnetic field.Because of this field the electron curves upward.The direction of the magnetic field is

A charged particle is moving with speed v perpendicular to a uniform magnetic field.A second identical charged particle is moving with speed 2v perpendicular to the same magnetic field.If the frequency of revolution of the first particle is f,the frequency of revolution of the second particle is

In a mass spectrometer,a singly-charged particle (charge e)has a speed of 1.0 × 106 m/s and enters a uniform magnetic field of 0.20 T.The radius of the circular orbit of the particle is 0.020 m.What is the mass of this particle? (e = 1.60 × 10-19C)

A circular loop of diameter 10 cm,carrying a current of 0.20 A,is placed inside a magnetic field = 0.30 T .The normal to the loop is parallel to a unit vector = -0.60 - 0.80 .Calculate the magnitude of the torque on the loop due to the magnetic field.

A wire segment 1.2 m long carries a current I = 3.5 A and is oriented as shown in the figure.A uniform magnetic field of magnitude 0.50 T pointing toward the -x direction is present as shown.The +z-axis points directly into the page.What is the magnetic force vector on the wire segment?

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A doubly charged ion (charge 2e)with velocity 6.9 × 10⁶ m/s moves in a circular path of diameter 60.0 cm in a magnetic field of 0.80 T in a mass spectrometer.What is the mass of this ion? (e = 1.60 × 10^-19C)

An electron moving perpendicular to a uniform magnetic field of 3.2 × 10^-2 T moves in a circle of radius 0.40 cm.How fast is this electron moving? (m_el = 9.11 × 10^-31 kg,

In a mass spectrometer,a singly-charged particle (charge e)has a speed of 1.0 × 10⁶ m/s and enters a uniform magnetic field of 0.20 T.The radius of the circular orbit of the particle is 0.020 m.What is the mass of this particle? (e = 1.60 × 10^-19C)