exam_3a_09_sol

# exam_3a_09_sol - Phys 2306 Exam 3 F09 Form A Phys 2306 Exam...

This preview shows pages 1–4. Sign up to view the full content.

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

View Full Document

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

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

Unformatted text preview: Phys. 2306 Exam 3 F09 Form A November 25, 2009 Phys. 2306 Exam 3 F09 Form A Solutions In cosmic ray experiments, particles travel downward (- j ) with speed v= 3 . 00 × 10 6 m/s. They enter a region of constant magnetic field, directed into the paper (- k ) at (x,y,z)=(0,0,0). They exit the field traveling upward at (x,y,z)=(1.00 m,0,0) with speed v’. 1) The ratio of the speeds v’/v is a) 1 b) 2 c) 1/2 d) 0 e) none of these Since F = q v × B , F · v = 0. No work is done on the particle by the magnetic force so its KE and speed don’t change, v’/v=1, (a). 2) The particle’s charge is a) positive b) negative c) 0 d) insufficient info Just after entering the field the force on the particle is in the +x ( i di- rection. Thus, F = F i = qvB (- j × - k ) = qvB i , q is positive, (a). 3) If the magnitude of the particle’s charge/mass= 0 . 240 × 10 8 C/m, what is the magnitude of the magnetic field in T? a) 0.125 b) 0.375 c) 0.5 d) 0.625 e) none of these In a constant B field with no velocity component in the field direction the mo- tion is circular motion, here a semi circle of radius 0.5 m. Thus mv 2 /R = qvB or B = v/ [ R ( q/m )] so B = 3 × 10 6 / [0 . 5( . 240 × 10 8 )] T = 0 . 25 T (e-none of the choices). There are three long wires that run parallel to the x axis and carry non- zero constant currents. Wire 1 passing through (y,z)=(0,0) carries current I in the +x i direction. There is no force/length on wire 2 passing through (y,z)=(a,0). On wire 3 passing through (y,z)=(3a,0) there is a force/length equal and opposite that on wire 1. 1 4) The current in wire 3 has magnitude, direction a) 2I, -x b) 2I, +x c) I/2, -x c) I/2, +x e) none of these 0 = d F 2 = I 2 d L 2 × B 2 . d L 2 = ± dL 2 i and B 2 = B 2 , 1 + B 2 , 3 = ( B 2 , 1 ± B 2 , 3 ) out ....
View Full Document

{[ snackBarMessage ]}

### Page1 / 6

exam_3a_09_sol - Phys 2306 Exam 3 F09 Form A Phys 2306 Exam...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online