Which fields) are created by an electron when it moves

The cavities are open along their length and connect the common cavity space. As electrons sweep past these openings, they induce a resonant, high-frequency radio field in the cavity, which in turn causes the electrons to bunch into groups. Cavity Magnetron Diagram : A cross-sectional diagram of a resonant cavity magnetron. Magnetic lines of force are parallel to the geometric axis of this structure.

The sizes of the cavities determine the resonant frequency, and thereby the frequency of emitted microwaves. The magnetron is a self-oscillating device requiring no external elements other than a power supply. The magnetron has practical applications in radar, heating as the primary component of a microwave oven , and lighting. Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles. It is used for determining masses of particles and determining the elemental composition of a sample or molecule.

Mass analyzers separate the ions according to their mass-to-charge ratio. The following two laws govern the dynamics of charged particles in electric and magnetic fields in a vacuum:. There are many types of mass analyzers, using either static or dynamic fields, and magnetic or electric fields, but all operate according to the above differential equation. The following figure illustrates one type of mass spectrometer. The deflections of the particles are dependent on the mass-to-charge ratio.

In the case of isotopic carbon dioxide, each molecule has the same charge, but different masses. The mass spectrometer will segregate the particles spatially allowing a detector to measure the mass-to-charge ratio of each particle. Since the charge is known, the absolute mass can be determined trivially. The relative abundances can be inferred from counting the number of particles of each given mass.

Mass Spectrometry : Schematics of a simple mass spectrometer with sector type mass analyzer. This one is for the measurement of carbon dioxide isotope ratios IRMS as in the carbon urea breath test.

Privacy Policy. Skip to main content. Search for:. Motion of a Charged Particle in a Magnetic Field. Electric vs. Magnetic Forces Electric and magnetic forces both affect the trajectory of charged particles, but in qualitatively different ways. Learning Objectives Compare the effects of the electric and the magnetic fields on the charged particle. Key Takeaways Key Points The force on a charged particle due to an electric field is directed parallel to the electric field vector in the case of a positive charge, and anti-parallel in the case of a negative charge.

It does not depend on the velocity of the particle. In contrast, the magnetic force on a charge particle is orthogonal to the magnetic field vector, and depends on the velocity of the particle. The right hand rule can be used to determine the direction of the force. An electric field may do work on a charged particle, while a magnetic field does no work. The Lorentz force is the combination of the electric and magnetic force, which are often considered together for practical applications.

Electric field lines are generated on positive charges and terminate on negative ones. The field lines of an isolated charge are directly radially outward.

The electric field is tangent to these lines. Magnetic field lines, in the case of a magnet, are generated at the north pole and terminate on a south pole. Magnetic poles do not exist in isolation. Like in the case of electric field lines, the magnetic field is tangent to the field lines.

Charged particles will spiral around these field lines. Key Terms orthogonal : Of two objects, at right angles; perpendicular to each other. Learning Objectives Identify conditions required for the particle to move in a straight line in the magnetic field. A particle with constant velocity will move along a straight line through space. In the case that the velocity vector is neither parallel nor perpendicular to the magnetic field, the component of the velocity parallel to the field will remain constant.

Key Terms straight-line motion : motion that proceeds in a single direction. Circular Motion Since the magnetic force is always perpendicular to the velocity of a charged particle, the particle will undergo circular motion.

Learning Objectives Describe conditions that lead to the circular motion of a charged particle in the magnetic field. Key Takeaways Key Points The magnetic field does no work, so the kinetic energy and speed of a charged particle in a magnetic field remain constant. The magnetic force, acting perpendicular to the velocity of the particle, will cause circular motion. Solving for r above yields the gryoradius, or the radius of curvature of the path of a particle with charge q and mass m moving in a magnetic field of strength B.

Key Terms gyroradius : The radius of the circular motion of a charged particle in the presence of a uniform magnetic field. Given by the equality of the centripetal force and magnetic Lorentz force. Helical Motion Helical motion results when the velocity vector is not perpendicular to the magnetic field vector.

Learning Objectives Describe conditions that lead to the helical motion of a charged particle in the magnetic field. Key Takeaways Key Points Previously, we have seen that circular motion results when the velocity of a charged particle is perpendicular to the magnetic field.

If the velocity is not perpendicular to the magnetic field, we consider only the component of v that is perpendicular to the field when making our calculations. This produces helical motion. Charges may spiral along field lines. If the strength of the magnetic field increases in the direction of motion, the field will exert a force to slow the charges and even reverse their direction. This is known as a magnetic mirror. Please enter the e-mail address you used to register to reset your password Enter e-mail address.

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Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Fields of a moving electron Ask Question. Asked 4 years, 2 months ago. Active 1 year ago. Viewed 4k times. So, the magnetic field here is due to both changing electric fields and currents.

Is this true? Improve this question. PhyEnthusiast PhyEnthusiast 2, 2 2 gold badges 12 12 silver badges 38 38 bronze badges. What an observer sees as electric or magnetic field depends on his frame of reference. Add a comment. Active Oldest Votes. Improve this answer. Frobenius Frobenius But my question still holds. Just because magnetic fields are present only in one frame of reference doesn't mean we should not talk about them, ryt!!!

Notice however that both the electric and the magnetic fields in the lab frame-of-reference will be time-dependent fields dynamic as opposed to static as the electron is moving in that frame-of-reference. In reality it is just information traveling in straight lines sent out from a moving object.