Author Question: Bert says that a charged particle in a vacuum can travel in a helix only if a uniform electric field ... (Read 126 times)

jessicacav · **on:** Jul 28, 2018

Bert says that a charged particle in a vacuum can travel in a helix only if a uniform electric field and a uniform magnetic field are both present and both parallel to the axis of the helix. Stuart says that only a magnetic field with a component parallel to the axis of the helix is needed. Which one, if either, is correct, and why?
a. Bert, because the charged particle's velocity can have a vertical component only if an electric field in the vertical direction is present.
b. Stuart, because a component of velocity in the vertical direction is not changed by a vertical component of a magnetic field. c. Bert, because a component of velocity in the vertical direction is changed by a vertical component of a magnetic field. d. Stuart, because an electric field in the vertical direction would cause the particle to come to a complete stop.
e. Neither, because particles cannot move in helical paths in the presence of magnetic and electric fields.

Question 2

A physicist claims that she has found a new particle with a mass 200 000 times the mass of the proton (1.67 10-27 kg) and a charge of 3.20 10-19 C. If she is correct, such a particle traveling in a circle in a uniform 5.00 T magnetic field at a velocity of 2 500 m/s will have a radius of
a. 0.261 m.
b. 0.522 m.
c. 1.04 m.
d. 3.27 m.
e. 3.13 1026 m.