Physics II

Time and Date Stamps (logged): 17:12:20 06-10-2020 ｰｶ涓ｱ浤ｯｯｵ涓ｯ浤ｯｱｯ Physics II

Principles of Physics (Phy 122) Test_4

Completely document your work and your reasoning.

You will be graded on your documentation, your reasoning, and the correctness of your conclusions.

** Write clearly in dark pencil or ink, on one side of the paper only. **

10-03-2001 20:45:48

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Name and Signature of Student _____________________________

Signed by Attendant, with Current Date and Time: ______________________

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Instructions:

Test is to be taken without reference to text or outside notes.
Graphing Calculator is allowed, as is blank paper or testing center paper.
No time limit but test is to be taken in one sitting.
Please place completed test in Dave Smith's folder, OR mail to Dave Smith, Science and Engineering, Va. Highlands CC, Abingdon, Va., 24212-0828 OR email copy of document to dsmith@vhcc.edu, OR fax to 276-739-2590. Test must be returned by individual or agency supervising test. Test is not to be returned to student after it has been taken. Student may, if proctor deems it feasible, make and retain a copy of the test..

Directions for Student:

Completely document your work.
Numerical answers should be correct to 3 significant figures. You may round off given numerical information to a precision consistent with this standard.
Undocumented and unjustified answers may be counted wrong, and in the case of two-choice or limited-choice answers (e.g., true-false or yes-no) will be counted wrong. Undocumented and unjustified answers, if wrong, never get partial credit. So show your work and explain your reasoning.
Due to a scanner malfunction and other errors some test items may be hard to read, incomplete or even illegible. If this is judged by the instructor to be the case you will not be penalized for these items, but if you complete them and if they help your grade they will be counted. Therefore it is to your advantage to attempt to complete them, if necessary sensibly filling in any questionable parts.
Please write on one side of paper only, and staple test pages together.

Test Problems:

. . . . . . . . . . . . . . . .

Constants

Constants:

k = 9*10^9 N m^2 / C^2	qE = 1.6 * 10^-19 C	h = 6.63 * 10^-34 J s
energy of n=1 orbital in hydrogen atom: -13.6 eV	k ' = 9 * 10^-7 T m / amp	atomic mass unit: 1.66 * 10^-27 kg
electron mass: 9.11 * 10^-31 kg	speed of light: 3 * 10^8 m/s	Avogadro's Number: 6.023 * 10^-23 particles/mole
Gas Constant: R = 8.31 J / (mole K)	proton mass: 1.6726 * 10^-27 kg	neutron mass: 1.6749 * 10^-27 kg

Problem Number 1

A magnetic field of magnitude 5.3 Tesla passes through a square loop with side 8.7 meters, with the field perpendicular to the plane of the loop. The loop is suddenly turned 90 degrees, so that its plane is parallel to the loop.

If the loop is turned in .022 seconds, what is the magnitude of the average rate of change of flux in the loop?

Problem Number 2

Find the magnitude of the magnetic field due to a straight current segment of length .033 m, at a distance of 3.7 meters from the segment, given that the vector from the midpoint of the segment to the point makes at angle 65 degrees with the segment, and that a current of 9.9 Amps flows in the segment.

Problem Number 3

At what Kelvin temperature will the thermal energy of electrons be greater than the energy binding an n = 1 electron to the proton in a hydrogen atom?

Problem Number 4

A beam consisting of 90 eV electrons (electron mass 9.11 * 10^-31 kg) is incident on a thin wafer of a crystal with layer spacing 2.8 Angstroms. Surprisingly we find that the electrons, which are particles, are scattered in such a way as to form an interference pattern identical to that of a wave. What will be the distance between central interference maxima at a distance of 10 cm from the wafer?

Problem Number 5

A beam of protons, each with rest mass about 1.6 * 10^-27 kg, are accelerated to near-light-speed velocities before entering a magnetic field of .6 Tesla. The magnetic field is directed perpendicular to the direction of the beam. Without taking account of the relativistic effect on mass, what should be the radius of curvature the protons if they are moving at 2.87 * 10^8 m/s as the beam passes through the magnetic field?

What should be the radius of curvature of the beam if we take relativistic effects into account?

What will happen to the radius of curvature as the velocities of the protons approach the speed of light?

Problem Number 6

An alpha particle consists of two protons and two neutrons. The neutrons are slightly more massive than the protons, but the average mass of all the particles is reasonably close to 1.6 * 10^-27 kg. The fundamental charge is 1.6 * 10^-19 Coulomb. If a beam of alpha particles moving at 4.5 * 10^6 m/s enters a magnetic field of .005 Tesla, with the velocity and field perpendicular to one another, what will be the radius of the circular path of the beam in the magnetic field?