# Problem: In the late 19th century, great interest was directed toward the study of electrical discharges in gases and the nature of so-called cathode rays. One remarkable series of experiments with cathode rays, conducted by J. J. Thomson around 1897, led to the discovery of the electron.With the idea that cathode rays were charged particles, Thomson used a cathode-ray tube to measure the ratio of charge to mass, q/m, of these particles, repeating the measurements with different cathode materials and different residual gases in the tube.In your experiment, you measure a total deflection of 4.12 cm when an electric field of 1.10×103 V/m is established between the plates (with no magnetic field present). When you add the magnetic field as described in Part C, to what value do you have to adjust its magnitude B0 to observe no deflection?Assume that the plates are 6.00 cm long and that the distance between them and the screen is 12.0 cm.Express your answer numerically in tesla.

###### FREE Expert Solution

Δy = 4.12 cm(1m/100cm) = 0.0412 cm

E0 = 1.10 × 103 V/m

d = 6.00 cm(1m/100cm) = 0.06 m

L = 12.0 cm(1m/100cm) = 0.12 m

m = 9.1 × 10-31 kg

e = 1.6 × 10-19 C ###### Problem Details

In the late 19th century, great interest was directed toward the study of electrical discharges in gases and the nature of so-called cathode rays. One remarkable series of experiments with cathode rays, conducted by J. J. Thomson around 1897, led to the discovery of the electron.

With the idea that cathode rays were charged particles, Thomson used a cathode-ray tube to measure the ratio of charge to mass, q/m, of these particles, repeating the measurements with different cathode materials and different residual gases in the tube.

In your experiment, you measure a total deflection of 4.12 cm when an electric field of 1.10×103 V/m is established between the plates (with no magnetic field present). When you add the magnetic field as described in Part C, to what value do you have to adjust its magnitude B0 to observe no deflection?

Assume that the plates are 6.00 cm long and that the distance between them and the screen is 12.0 cm.