Reference no: EM13339828
A device called a velocity selector is a tube with a crossed electric and magnetic fields set up so that the particle entering with a velocity v_0 along the axis of the tube experiences zero net force. This particle can travel directly along the tube and then exit the tube, but particles with any other velocity experience electric and/or magnetic forces which cause them to crash into the walls of the tube. Consider a tube which has a height = 1m and a radius r=2.5cm. Particles enter at the top and exit (if they exit) at the bottom.
A) Sketch the tube and the E and B fields.
B) Find the ratio of electric and magnetic field strengths, E/B, given v_0, q (the charge of an entering particle) and m (the mass of an entering particle).
C) So far we have determined the required E/B ratio, but not the value of E or B. One way to do this is to specify how selective the device must be; in other words, how much a particle's speed can differ from v_0 and still exit the device. Your customer's requirement is to restrict the particle to the range I v - v_0 I < 0.01v_0. Use this to determine E and B in terms of the other variables. Justify any approximations you make.
D) For v_0=10^4 m/s and q/m typical of atomic particles (about 10^-8), how practical would it be to generate the required B field: would you use an average permanent magnet, an extra-strong (and therefore expensive) permanent magnet, an average elctromagnet, or an extra-strong (and therefore expensive) electromagnet?