A cathode ray tube consists of a \"gun\" to shoot a beam of electrons horizontal
ID: 1910607 • Letter: A
Question
A cathode ray tube consists of a "gun" to shoot a beam of electrons horizontally toward a vertical deflector as shown. Both sections are parallel-plate capacitors, with uniform electric field of 1.2x10^5 N/C. (The electron starts from rest) Note you may also leave your answers in terms of the elementary charge, e and mass of an electron, me. You may also ignore the weight of the electron, since it is much less than the EM forces. a. What is the force on the electron as it passes through the gun? b.Does it gain or lose electrostatic potential energy? Explain. (Quantitatively or Qualitatively) c.What is the capacitance d.If you added a uniform magnetic field within the deflector, what would be the total force? e.In which direction must the field be to deflect the electron downward, instead of upward?
Explanation / Answer
a) F = qE = 1.6E-19*1.2E5=1.92E-14 N b) dU = q dV = -e dV since dV>0 then dURelated Questions
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