{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# hw 17 - nguyen(jmn727 homework 17 Turner(59070 This...

This preview shows pages 1–3. Sign up to view the full content.

nguyen (jmn727) – homework 17 – Turner – (59070) 1 This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Can an electron at rest in a magnetic field be set into motion by the magnetic field? What if it were at rest in an electric field? 1. no; yes correct 2. yes for both 3. None of these 4. It depends on the intensity of the fields, which is not provided in the problem. 5. no for both 6. yes; no Explanation: An electron has to move across lines of magnetic field in order to feel a magnetic force, so an electron at rest in a stationary magnetic field will feel no force to set it in motion. However, an electron in an electric field will accelerate regardless of its current state of motion. 002 10.0 points Two charged particles are projected into a magnetic field that is perpendicular to their initial velocities. If the charges are deflected in opposite di- rections, what does this tell you about them? (Ignore the interaction between these two par- ticles.) 1. One particle is an electron and the other is a positive ion. 2. Their velocities have opposite direc- tions. 3. One particle comes from nature; the other is man-made. 4. They have opposite charges if their initial velocities are in the same direction. correct Explanation: The magnetic force exerted on a particle depends on the charge of the particle, the velocity of the particle and the magnitude and direction of the magnetic field. If two particles have the same velocities but opposite charges they feel opposite magnetic forces so that they are deflected in opposite directions. But, this does not guarantee that one of them is an electron. 003 10.0 points A charged particle beam (shot horizontally) moves into a region where there is a constant magnetic field of magnitude 0 . 00127 T that points straight down. The charged particles in the beam move in a circular path of radius 2 . 33 cm. If the charged particles in the beam were accelerated through a potential difference of 280 V, determine the charge to mass ratio of the charged particles in the beam. Correct answer: 6 . 39542 × 10 11 C / kg. Explanation: Let : B = 0 . 00127 T , r = 2 . 33 cm = 0 . 0233 m , and V = 280 V . The kinetic energy of the electron after accel- erated through the potential difference is 1 2 m v 2 = q V . And the centrifugal force experienced by the charge particle in the magnetic field is q v B sin(90 ) = m v 2 r then we have v = q b r m then 1 2 m q 2 B 2 r 2 m 2 = q V .

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
nguyen (jmn727) – homework 17 – Turner – (59070) 2 Thus , the charge-to-mass ratio is R = q m = 2 V B 2 r 2 = 2(280 V) (0 . 00127 T) 2 (0 . 0233 m) 2 = 6 . 39542 × 10 11 C / kg . 004 (part 1 of 2) 10.0 points A particle of mass m and charge q starts from rest at the origin (point A in the figure below).
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern