In 1897, J. J. Thomson "discovered" the electron by measuring the charge-to-mass ratio of "catho

1. For the experiment to work, it is not necessary that E = B. However, for the beam to pass str

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In 1897, J. J. Thomson "discovered" the electron by measuring the charge-to-mass ratio of "cathode rays" (actually, streams of electrons, with charge q_e and mass m_e). First he passed the beam through uniform crossed electric and magnetic fields E and B (mutually perpendicular, and both of them perpendicular to the beam), and adjusted the electric field until he got zero deflection. +ve terminal of HV power supply for charged plates Helmholtz coils on opposite sides of the sealed glass tube Sealed glass tube Tape measure Charged plates partly obscured by the Helmholtz coils J J Thomson's Cathode Ray Tube for determining q/m ratio of the electron a) For this experiment to work must E ? B or is this a matter of convenience? Explain. b) What was the speed of the particles when the particles went straight through (in terms of |E| and |B|)? c) Then he turned off the electric field, and measured the radius of curvature, R, of the beam, as deflected by the magnetic field alone. In terms of R, |E| and |B|, what is the charge-to-mass ratio (q/m) of the particles?

          In 1897, J. J. Thomson "discovered" the electron by measuring the charge-to-mass ratio of "cathode rays" (actually, streams of electrons, with charge q_e and mass m_e). First he passed the beam through uniform crossed electric and magnetic fields E and B (mutually perpendicular, and both of them perpendicular to the beam), and adjusted the electric field until he got zero deflection.

+ve terminal of HV power supply for charged plates
Helmholtz coils on opposite sides of the sealed glass tube
Sealed glass tube
Tape measure
Charged plates partly obscured by the Helmholtz coils
J J Thomson's Cathode Ray Tube for determining q/m ratio of the electron

a) For this experiment to work must E ? B or is this a matter of convenience? Explain.
b) What was the speed of the particles when the particles went straight through (in terms of |E| and |B|)?
c) Then he turned off the electric field, and measured the radius of curvature, R, of the beam, as deflected by the magnetic field alone. In terms of R, |E| and |B|, what is the charge-to-mass ratio (q/m) of the particles?

In 1897, J. J. Thomson "discovered" the electron by measuring the charge-to-mass ratio of "cathode rays" (actually, streams of electrons, with charge qe and mass me). First he passed the beam through uniform crossed electric and magnetic fields E and B (mutually perpendicular, and both of them perpendicular to the beam), and adjusted the electric field until he got zero deflection.

+ve terminal of HV power supply for charged plates
Helmholtz coils on opposite sides of the sealed glass tube
Sealed glass tube
Tape measure
Charged plates partly obscured by the Helmholtz coils
J J Thomson's Cathode Ray Tube for determining q/m ratio of the electron

a) For this experiment to work must E ? B or is this a matter of convenience? Explain.
b) What was the speed of the particles when the particles went straight through (in terms of |E| and |B|)?
c) Then he turned off the electric field, and measured the radius of curvature, R, of the beam, as deflected by the magnetic field alone. In terms of R, |E| and |B|, what is the charge-to-mass ratio (q/m) of the particles?

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