{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# q4_key - PHY-2054C-002 Fall 2008 Instructor Dr Bhattacharya...

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: PHY-2054C-002, Fall 2008 Instructor: Dr. Bhattacharya Quiz #4-KEY, Thursday, Sept 25 1. A beam of protons is accelerated through a potential difference of 1.5 kV and then enters a uniform magnetic field traveling perpendicular to the field. Y 11 00 11 00 11 00 11 00 11 00 11 00 11 00 11 00 11 00 11 00 11 00 11 00 1 11 11 0 00 00 1 11 11 0 00 00 11 00 11 00 1 11 11 0 00 00 1 11 11 0 00 00 1 11 11 0 00 00 1 11 11 0 00 00 1 11 11 0 00 00 1 11 11 0 00 00 1 11 11 0 00 00 1 11 11 0 00 00 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 11 0 00 1 11 0 00 1 0 1 0 1 0 1 0 1 0 11 00 11 00 11 00 11 00 11 00 11 00 1 0 11 11 00 Particle Trajectory 00 1 11 0 00 11 00 1 11 0 00 1 11 0 00 1 11 0 00 1 11 0 00 1 11 0 00 X Z (a) Indicate with an arrow on the circle in figure above, if the path is clockwise or anticlockwise. Since v = v^ and B = B^, the right had rule gives F = F(-^). the proton will be x z y experiencing a downward force resulting in a clockwise trajectory (b) What magnitude of field is needed to bend these protons in a circular arc of diameter 3.0 m mp v 2 Bp qv = R mp v Bp = qR To obtain the velocity of the proton one uses energy conservation so that 1 mp v 2 = qV 2 v= 2qV = 53.61 104 m/s. mp (1) (2) Substituting this value of v in Eqn. 2, we get Bp = 37.3 10-4 T. (c) What magnetic field would be needed to produce a path with the same diameter if the particles were electrons having the same speed as the protons? From Eqn. 2 it follows that the magnetic field for an electron mp v me me v = = Bp /1834 T = 0.029 10-4 T Be = qR qR mp (d) If the strength of the magnetic field were increased three times that you obtain in part (b), what would be the diameter of the circular path ? From Eqn. 2 it follows that one needs to increase the field 3 times to have the radius shortened to 1/3 rd of its original value. ...
View Full Document

{[ snackBarMessage ]}