HW08 Chapter 27 and Chapter 28 (part 1) PDF

Preview

Summary

University physics chapter 27 and 28 answers or mastering physics assignment...

Description

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

HW08: Chapter 27 and Chapter 28 (part 1) Due: 10:30am on Wednesday, June 2, 2021 You will receive no credit for items you complete after the assignment is due. Grading Policy

Exercise 27.8 A particle with charge \(-\) 5.80 \({\rm nC}\) is moving in a uniform magnetic field \(\vec{B}=-(\) 1.27 \({\rm T}\) )\(\hat{k}\). The magnetic force on the particle is measured to be \(\vec{F}=-(\) 3.20×10−7 \({\rm N}\) \()\hat{i} + (\) 7.60×10−7 \({\rm N}\) \()\hat{j}\)

Part A Are there components of the velocity that are not determined by the measurement of the force? ANSWER:

yes no

Part B Complete previous part(s)

Instructors: View all hidden parts

Part C Complete previous part(s)

Instructors: View all hidden parts

Part D Calculate the scalar product \(\vec{v} \cdot \vec{F}\). ANSWER: VxFx+VyFy+VzFz= (Fy/-qBz)Fx+ (Fx/qBz)Fy=0 \(\vec{v} \cdot \vec{F}\) =

Zero

\({\rm m/s\cdot N}\)

Part E What is the angle between \(\texttip{\vec{v}}{v_vec}\) and \(\vec{F}\)? Give your answer in degrees. ANSWER: \(\theta\) =

90

\(^\circ\)

Exercise 27.19 In an experiment with cosmic rays, a vertical beam of particles that have charge of magnitude 3\(e\) and mass 12 times the proton mass enters a uniform horizontal magnetic field of 0.250 \({\rm T}\) and is bent in a semicircle of diameter 95.0 \({\rm cm}\), as shown in .

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

1/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

Part A Find the speed of the particles. ANSWER: \(v\) =

2.84 x10^6

\({\rm m/s}\)

Part B Find the sign of particles' charge. ANSWER:

positive negative

Part C Is it reasonable to ignore the gravity force on the particles? ANSWER: reasonable unreasonable

Part D How does the speed of the particles as they enter the field compare to their speed as they exit the field? ANSWER:

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

2/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

equal nonequal

Exercise 27.24 A beam of protons traveling at 1.60 \({\rm km/s}\) enters a uniform magnetic field, traveling perpendicular to the field. The beam exits the magnetic field, leaving the field in a direction perpendicular to its original direction (the figure ). The beam travels a distance of 1.70 \({\rm cm}\) while in the field.

Part A What is the magnitude of the magnetic field? ANSWER: \(B\) =

154.2 x 10^-5

\(\rm T\)

Mass Spectrometer J. J. Thomson is best known for his discoveries about the nature of cathode rays. Another important contribution of his was the invention, together with one of his students, of the mass spectrometer. The ratio of mass \(\texttip{m}{m}\) to (positive) charge \ (\texttip{q}{q}\) of an ion may be accurately determined in a mass spectrometer. In essence, the spectrometer consists of two regions: one that accelerates the ion through a potential difference \(\texttip{V}{V}\) and a second that measures its radius of curvature in a perpendicular magnetic field as shown in . The ion begins at potential \(\texttip{V}{V}\) and is accelerated toward zero potential. When the particle exits the region with the electric field it will have obtained a speed \(\texttip{u}{u}\).

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

3/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

Part A With what speed \(\texttip{u}{u}\) does the ion exit the acceleration region? Find the speed in terms of \(\texttip{m}{m}\), \(\texttip{q}{q}\), \(\texttip{V}{V}\), and any constants. You did not open hints for this part. ANSWER: \(\texttip{u}{u}\) =

(2qV/m)^1/2

Part B After being accelerated, the particle enters a uniform magnetic field of strength \(\texttip{B_{\rm 0}}{B_0}\) and travels in a circle of radius \(\texttip{R}{R}\) (determined by observing where it hits on a screen--as shown in the figure). The results of this experiment allow one to find \(m/q\) in terms of the experimentally measured quantities such as the particle radius, the magnetic field, and the applied voltage. What is \(m/q\)? Express \(\texttip{m/q}{m/q}\) in terms of \(\texttip{B_{\rm 0}}{B_0}\), \(\texttip{V}{V}\), \(\texttip{R}{R}\), and any necessary constants. You did not open hints for this part. ANSWER: \(m/q\) =

R*Bo ^2/2v

Motion of Electrons in a Magnetic Field An electron of mass \(\texttip{m}{m}\) and charge \(-e\) is moving through a uniform magnetic field \(\vec{B}=(B_x,0,0)\) in vacuum. At the origin, it has velocity \(\vec{v} = (v_x,v_y,0)\), where \(v_x > 0\) and \(v_y > 0\). A screen is mounted perpendicular to the x axis at a distance \(\texttip{D}{D}\) from the origin. Throughout, you can assume that the effect of gravity is negligible.

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

4/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

Part A First, suppose \(B_x = 0\). Find the y coordinate \(\texttip{y}{y}\) of the point at which the electron strikes the screen. Express your answer in terms of \(\texttip{D}{D}\) and the velocity components \(\texttip{v_{\mit x}}{v_x}\) and \ (\texttip{v_{\mit y}}{v_y}\). You did not open hints for this part. ANSWER: \(\texttip{y}{y}\) =

vyD/Vx

Part B Now suppose \(B_x > 0\), and another electron is projected in the same manner. Which of the following is the most accurat qualitative description of the electron's motion once it enters the region of nonzero magnetic field? ANSWER:

The electron decelerates before coming to a halt and turning around while always moving along a straight line. The electron's motion will be unaffected. (It will continue moving in a straight line with the same constant velocity.) The electron moves in a circle in the xy plane. The electron moves along a helical path about an axis parallel to the field lines with constant radius and constant velocity in the x direction.

Part C Complete previous part(s)

Instructors: View all hidden parts

Exercise 28.4

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

5/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

An alpha particle (charge +2\(e\)) and an electron move in opposite directions from the same point, each with the speed of 2.10×105 \({\rm \;\rm m/s}\) .

Part A Find the magnitude of the total magnetic field these charges produce at point \(P\), which is 8.25 \({\rm \;nm}\) from each charge. Express your answer with the appropriate units. ANSWER: \(B\) =

9.519 x 10^-5

Part B Find the direction of this magnetic field. ANSWER: into the page to the right out of the page to the left

Exercise 28.6 Positive point charges \(\texttip{q}{q}\) = 9.00 \({\rm \mu C}\) and \(q'=\) 4.00 \({\rm \mu C}\) are moving relative to an observer at point \(P\), as shown in the figure . The distance \(d\) is 0.110 \({\rm m}\) , \(\texttip{v}{v}\) = 4.60×106 \({\rm m/s}\) , and \(v'=\) 9.20×106 \({\rm m/s}\) .

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

6/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

Part A When the two charges are at the locations shown in the figure, what is the magnitude of the net magnetic field they produce at point \(P\)? ANSWER: \(B\) =

6.46 x 10^-4

\(\rm T\)

Part B What is the direction of the net magnetic field at point \(P\)? ANSWER:

into the page out of the page

Part C What is the magnitude of the electric force that each charge exerts on the other? ANSWER: \(F_C\) =

3.14 x 10^9

\(\rm N\)

Part D What is the direction of the electric force that each charge exerts on the other? ANSWER:

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

7/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

The force on the upper charge points down. The force on the upper charge points up.

Part E What is the magnitude of the magnetic force that each charge exerts on the other? ANSWER: \(F_B\) =

6.686

\(\rm N\)

Part F What is the direction of the magnetic force that each charge exerts on the other? ANSWER:

The force on the upper charge points down. The force on the upper charge points up.

Part G What is the ratio of the magnitude of the electric force to the magnitude of the magnetic force? ANSWER: \(\large{\frac{F_C}{F_B}}\) =

2.12 x 10-^9

Part H Complete previous part(s)

Instructors: View all hidden parts

Part I Complete previous part(s)

Instructors: View all hidden parts

Exercise 28.8 An electron and a proton are each moving at 780 \({\rm \;km/s}\) in perpendicular paths as shown in .

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

8/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

Part A At the instant when they are at the positions shown, find the magnitude of the total magnetic field they produce at the origin Express your answer with the appropriate units. ANSWER: \(B\) =

1.279 mT

Part B Find the direction of the total magnetic field they produce at the origin. ANSWER: the \(+y\) direction into the page out of the page the \(+x\) direction

Part C Find the magnitude of the magnetic field the electron produces at the location of the proton. Express your answer with the appropriate units. ANSWER: \(B\) =

2.375 X 10^-4 T

Part D https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

9/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

Find the direction of the magnetic field the electron produces at the location of the proton. ANSWER:

out the page the \(+y\) direction into the page the \(-x\) direction

Part E Find the magnitude of the total magnetic force that the electron exerts on the proton. Express your answer with the appropriate units. ANSWER: \(F_{mag}\) =

2.964 x 10^-17 N

Part F Find the direction of the total magnetic force that the electron exerts on the proton. ANSWER: into the page the \(+x\) direction out of the page the \(+y\) direction

Part G Find the magnitude of the total electrical force that the electron exerts on the proton. Express your answer with the appropriate units. ANSWER: \(F_{\rm elec}\) =

5.61 X 10^-12 N

Part H Find the direction of the total electrical force that the electron exerts on the proton. ANSWER:

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

10/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

\(\phi\) =

129

\(^\circ\) counterclockwise from the +\(x\)-axis

Exercise 28.12 Two parallel wires are 4.60 \({\rm cm}\) apart and carry currents in opposite directions, as shown in the figure .

Part A Find the magnitude of the magnetic field at point \(P\) due to two 1.50\(-\,{\rm mm}\) segments of wire that are opposite eac other and each 8.00 \({\rm cm}\) from \(P\). ANSWER: \(B\) =

2.039 x 10^-7

\(\rm T\)

Part B Find the direction of the magnetic field at point \(P\). ANSWER:

out of the page into the page

Exercise 28.14 A square wire loop 15.0 \({\rm \;\rm cm}\) on each side carries a clockwise current of 6.00 \({\rm \;\rm A}\) .

Part A

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

11/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

Find the magnitude of the magnetic field at its center due to the four 1.50 -\(\rm mm\) wire segments at the midpoint of each side. Express your answer with the appropriate units. ANSWER: \(B\) =

6.4 x 10^-7 T

Part B Find the direction of this magnetic field. ANSWER:

out of the page into the page to the left from the wire to the right from the wire

Exercise 28.21 A long, straight wire lies along the y-axis and carries a current 8.00 \({\rm A}\) in the -y-direction . In addition to the magnetic fiel due to the current in the wire, a uniform magnetic field \(\vec{B}_0\) with magnitude \(1.50 \times 10^{ - 6} \, {\rm T}\) is in the +x-direction.

Part A What is the magnitude of the total field at the point x = 0, z = 1.00 m in the xz-plane? ANSWER: \(B\) =

(-1 x10^-7 T ) j^ \({\rm T}\)

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

12/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

Part B What is its direction? ANSWER:

90

\(^\circ\) from +x to +z axis.

Part C What is the magnitude of the total field at the point x = 1.00 m, z = 0 in the xz-plane? ANSWER: \(B\) =

2.19 x 10^-6 T

\({\rm T}\)

Part D What is its direction? ANSWER: 46.8

\(^\circ\) from +x to +z axis.

Part E What is the magnitude of the total field at the point x = 0, z = -0.25 m in the xz-plane? ANSWER: \(B\) =

(7.9 x 10^-6 T ) ^j

\({\rm T}\)

Part F What is its direction? ANSWER: 90

\(^\circ\) from +x to +z axis.

Exercise 28.30 Two long, parallel wires are separated by a distance of 2.20 \({\rm {\rm cm}}\) . The force per unit length that each wire exerts on the other is 4.30×10−5 \({\rm {\rm N/m}}\) , and the wires repel each other. The current in one wire is 0.660 \({\rm {\rm A}}\) .

Part A What is the current in the second wire? https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

13/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

ANSWER: \(I\) =

7.16

\({\rm A}\)

Part B Are the two currents in the same direction or in opposite directions? ANSWER:

In the same direction In opposite direction

Exercise 28.39 Two round concentric metal wires lie on a tabletop, one inside the other. The inner wire has a diameter of 24.0 \({\rm {\rm cm}}\) and carries a clockwise current of 20.0 \({\rm {\rm A}}\) , as viewed from above, and the outer wire has a diameter of 40.0 \({\rm {\rm cm}}\) .

Part A What must be the direction (as viewed from above) of the current in the outer wire so that the net magnetic field due to this combination of wires is zero at the common center of the wires? ANSWER: The current's direction must be clockwise. The current's direction must be counterclockwise.

Part B What must be the magnitude of the current in the outer wire so that the net magnetic field due to this combination of wires i zero at the common center of the wires? ANSWER: \(I\) =

12

\({\rm A}\)

Exercise 28.42 As a new electrical technician, you are designing a large solenoid to produce a uniform 0.140-\(\rm T\) magnetic field near the center of the solenoid. You have enough wire for 4000 circular turns. This solenoid must be 58.0 \({\rm cm}\) long and 2.80 \({\rm cm}\) in diameter.

Part A https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

14/15

6/1/2021

HW08: Chapter 27 and Chapter 28 (part 1)

What current will you need to produce the necessary field? Express your answer to three significant figures and include the appropriate units. ANSWER: \(I\) =

16.154 A

Score Summary: Your score on this assignment is 0.0%. You received 0 out of a possible total of 6 points.

https://session.masteringphysics.com/myct/assignmentPrintView?displayMode=studentView&assignmentID=9149169

15/15...