In his famous experiment with electrons, j. j. thompson measured the "charge-to-mass-ratio" r = en, where e is the electron's charge and m is its mass. a modern classroom version of this experiment finds the ratio r by accelerating electrons through a voltage vand then bending them in a magnetic field. the ratio r=e/m is given by the formula: 125 d2v in this experiment, ilo is the permeability constant of a vacuum (equal to 4π x 10" na exactly) and n is the number of turns in the coil that produces the magnetic field. d is the diameter of the field coils, v is the voltage that accelerates the electrons, d is the diameter of the electro curved path, and / is the current in the field coils. a student makes the following measurements: n= 72 (exactly) d-661 ± 2 mm v= 45.0 ± 0.2 volts d=91.4±0.5 mm |= 2.48 ± 0.04 amps (a) find the student's answer for the charge-to-mass ratio of the electron, with its uncertainty. (assume all uncertainties are independent and random.) (b) how well does this answer agree with the accepted value r= 1.759x10" c/kg?