FA20.2 Forces on Wires and Particles
I explain the directions of the vectors with a video camera at my desk:
1. 18.2 A of current flow east along a wire in a magnetic field of 0.0150 T that is 17.0o east of North. What force acts on the wire if it is 113 m long? (Magnitude and direction)
(29.5 N Up)
2. A 4.2 Amp current flows North in a wire that is 12.1 cm long. What is the magnetic field (Assume it is perpendicular) if the wire experiences a vertically upward force of 12.15 N? (Magnitude and direction)
(24 T West)
3. An electron travels at 3.5 x 104 m/s to the North, and experiences a force of 2.1 x 10-14 N vertically downward. What is the magnitude and direction of the magnetic field exerting this force?
(3.7 T W)
4. A proton is going 1.71 x 105 m/s in the plane of the page in a 2.30 T magnetic field out of this page. What is the radius of its path? Which direction does it circle, ACW or CW?
(7.76x10-4 m, CW)
5. What electric field in what direction would make the particle go straight up the page in the previous problem?
(3.93x105 N/C, Left)
More Practice Problems: Worksheet-Practice20.2.docx
Practice for 20.2
1. a. 26.1 A of current flow north along a wire in a magnetic field of 0.0154 T that is 62.0o east of South. What force acts on the wire if it is 132 m long? (Magnitude and direction) (46.8 N vert down) FA20 2 #1a
b. A 1.48 Amp current flows South in a wire that is17.2 cm long. What is the magnetic field (Assume it is perpendicular) if the wire experiences a vertically upward force of 3.17 N? (Magnitude and direction) (12.5 T east) FA20 2 #1b
c. A moving electron travels through a 2.43 T upward magnetic field, and experiences a force of 7.2 x 10-12 N to the east. What is the magnitude and direction of the particle’s velocity? (1.8x107 m/s south) FA20 2 #1c
d. A mystery particle with a mass of 6.69 x 10-27 kg traveling 2.96 x 106 m/s in a 1.21 T magnetic field out of this page revolves clockwise with a radius 5.11 x 10-2 m. What is the charge of the particle, and is it positive, or negative? (3.20x10-19 C, positive) FA20 2 #1d
e. What electric field in what direction would make the particle go straight down the page in the previous problem? (3.58x106 N/C right) FA20 2 #1e
2. a. 21.4 A of current flow west along a wire in a magnetic field of 0.0305 T that is 78.0o north of east. What force acts on the wire if it is 215 m long? (Magnitude and direction) (137 N vert down) FA20 2 #2a
b. A current of 31.8 A flowing in a wire experiences a force to the North of 1.61 N in a region where there is a magnetic field of 0.597 T vertically upward. What is the length of the wire perpendicular to the magnetic field, and in what direction does the current flow? (0.0848 m, west) FA20 2 #2b
c. A proton travels at 2.17 x 103 m/s vertically upward, and experiences a force of 8.1 x 10-16 N to the east. What is the magnitude and direction of the magnetic field exerting this force? (2.33 T south) FA20 2 #2c
d. An electron is going 2.47 x 106 m/s in the plane of the page in a 0.128 T magnetic field out of this page. What is the radius of its path? Which direction does it circle, ACW or CW? (1.10x10-4 m, ACW) FA20 2 #2d
e. What electric field in what direction would make the particle go straight to the right on the page(è) in the previous problem? (3.16x105 N/C up the page) FA20 2 #2e
3. a. 11.8 A of current flow east along a wire in a magnetic field of 0.0451 T that is 32.0o east of North. What force acts on the wire if it is 126 m long? (Magnitude and direction) (56.9 N vert up) Practice 20 2 #3a
b. A vertical wire 35.7 cm long experiences a 0.821 N force to the East in a 0.0783 T Northerly magnetic field. What is the current flowing in the wire, and which way does it flow? (Assume it is perpendicular) (29.4 A vert down) Practice 20 2 #3b
c. A moving electron travels through a 0.78 T westerly magnetic field, and experiences a force of 2.5 x 10-14 N vertically upward. What is the magnitude and direction of the particle’s velocity? (2.0x105 m/s south) Practice 20 2 #3c
d. A proton traveling at 4.81 x 106 m/s in the plane of this page travels anti-clockwise in a circle with a radius of 2.87 mm (2.87 x 10-3 m). What is the magnitude and direction of the magnetic field that effects this? (17.5 T into the page)
e. What electric field in what direction would make the particle go straight to the left on the page (ç) in the previous problem? (8.42x107 N/C up the page)
Video that solves both d and e: Practice 20 2 #3de
4. a. 13.1 A of current flow south along a wire in a magnetic field of 0.0241 T that is 56.0o north of West. What force acts on the wire if it is 501 m long? (Magnitude and direction) (88.4 N vert down)
b. A 45.7 cm long wire experiences a force of 3.12 N to the North in a vertically upward 0.0382 T magnetic field. What is the current, and in what direction does it flow? (Assume it is perpendicular) (179 A West)
c. A proton travels at 5.2 x 103 m/s to the North through a vertically downward 0.45 T magnetic field. What is the magnitude and direction of the force acting on the particle? (3.7x10-16 N West)
d. An electron in a 0.00287 T magnetic field out of this page goes in a circle with a radius of 0.0781 m. What is the electron’s velocity, and which direction does it circle, ACW or CW? (3.94x107 m/s, ACW)
e. What electric field in what direction would make the particle go straight up the page in the previous problem? (1.13x105 N/C left)
5. a. 15.2 A of current flow north along a wire in a magnetic field of 0.0127 T that is 23.0o south of East. What force acts on the wire if it is 157 m long? (Magnitude and direction) (vert down 27.9 N)
b. A 3.2 Amp current flows West in a wire that is 32.1 cm long. What is the magnetic field (Assume it is perpendicular) if the wire experiences a vertically downward force of 4.17 N? (Magnitude and direction) (4.1 T North)
c. An electron travels at 7.8x105 m/s to the South, and experiences a force of 4.3 x 10-14 N to the East. What is the magnitude and direction of the magnetic field exerting this force? (0.34 T vert up)
d. A proton in is going 3.71x105 m/s in the plane of the page. A magnetic field is making it travel in clockwise circles with a radius of 2.37 m. What is the magnitude and direction of the magnetic field? (0.00163T out of page)
e. What electric field in what direction would make the particle go straight down the page in the previous problem? (607 N/C right)