In the d state, the electron has a magnetic moment with five possible values for the z -component of this magnetic moment. In this case, the magnetic moment can point in five different polar directions. A hydrogen atom has a magnetic field, so we expect the hydrogen atom to interact with an external magnetic field—such as the push and pull between two bar magnets. From Force and Torque on a Current Loop , we know that when a current loop interacts with an external magnetic field , it experiences a torque given by.
This torque acts to rotate the magnetic moment vector of the hydrogen atom to align with the external magnetic field. Because mechanical work is done by the external magnetic field on the hydrogen atom, we can talk about energy transformations in the atom. The potential energy of the hydrogen atom associated with this magnetic interaction is given by Figure :. If the magnetic moment is antiparallel to the external magnetic field, the potential energy is large, but if the magnetic moment is parallel to the field, the potential energy is small.
The energy of the system is conserved, however, because a drop in potential energy produces radiation the emission of a photon. These energy transitions are quantized because the magnetic moment can point in only certain directions. If the external magnetic field points in the positive z -direction, the potential energy associated with the orbital magnetic dipole moment is.
For example, in the electron state, the total energy of the electron is split into three distinct energy levels corresponding to. The splitting of energy levels by an external magnetic field is called the Zeeman effect. Ignoring the effects of electron spin, transitions from the state to a common lower energy state produce three closely spaced spectral lines Figure , left column.
Likewise, transitions from the state produce five closely spaced spectral lines right column. The separation of these lines is proportional to the strength of the external magnetic field. This effect has many applications.
A magnetogram of the Sun. The bright and dark spots show significant magnetic activity at the surface of the Sun. The energy levels of a hydrogen atom associated with orbital angular momentum are split by an external magnetic field because the orbital angular magnetic moment interacts with the field.
The quantum numbers of an electron in a hydrogen atom can be used to calculate the magnitude and direction of the orbital magnetic dipole moment of the atom. Conceptual Questions Explain why spectral lines of the hydrogen atom are split by an external magnetic field. What determines the number and spacing of these lines? A hydrogen atom is placed in a magnetic field. Which of the following quantities are affected? The work done on the hydrogen atom rotates the atom, so the z -component of angular momentum and polar angle are affected.
However, the angular momentum is not affected. On what factors does the orbital magnetic dipole moment of an electron depend? Find the magnitude of the orbital magnetic dipole moment of the electron in in the 3 p state. Express your answer in terms of. This can be represented by the torque that a material experiences when added to a magnetic field.
The stronger the magnetic moment, the stronger the magnetic field and the stronger the torque. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Updating… Please wait. Unable to process the form. Check for errors and try again. Thank you for updating your details. Log In. Sign Up. Become a Gold Supporter and see no ads. Log in Sign up.
Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free! Log in Sign Up. Save Word. Definition of magnetic moment. First Known Use of magnetic moment , in the meaning defined above. Learn More About magnetic moment. Share magnetic moment Post the Definition of magnetic moment to Facebook Share the Definition of magnetic moment on Twitter. Time Traveler for magnetic moment The first known use of magnetic moment was in See more words from the same year.
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