Electrons in a magnetic/electric field

In summary, the textbook explains that by observing the behavior of moving electrons, it is possible to determine whether an electric field, a magnetic field, or both are present in a certain region of space. If the speed of the electrons changes as they are being deflected, then an electric field is present. However, if the electrons are being deflected but their speed remains constant, then only a magnetic field is present. This is because the forces of electric and magnetic fields act differently on electrons, resulting in different trajectories.
  • #1
gokuls
35
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How could you tell whether moving electrons in a certain region of space are being deflected by an electric field or by a magnetic field (or both)?

The answer from the textbook is:
If the moving electrons are changing speed as they are being deflected, then an electric field is present. This will be the case whether or not a magnetic field exists in the same region of space. If the moving electrons are being deflected but they are not changing speed, then only a magnetic field is present.

I don't understand this explanation, why would the speed only change in an electric field, but not in a magnetic field?

Thanks,
 
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  • #2
gokuls said:
How could you tell whether moving electrons in a certain region of space are being deflected by an electric field or by a magnetic field (or both)?

The answer from the textbook is:
If the moving electrons are changing speed as they are being deflected, then an electric field is present. This will be the case whether or not a magnetic field exists in the same region of space. If the moving electrons are being deflected but they are not changing speed, then only a magnetic field is present.

I don't understand this explanation, why would the speed only change in an electric field, but not in a magnetic field?

Thanks,

Consider, separately, how the magnetic and electric forces are applied to the electron. What directions do they act? What do the resulting trajectories look like?
 

1. What is the relationship between electrons and magnetic fields?

The relationship between electrons and magnetic fields is based on the principle of electromagnetism. When an electron is in motion, it creates a magnetic field around it. Likewise, a magnetic field can influence the motion of an electron, causing it to move in a curved path.

2. How do electrons behave in an electric field?

In an electric field, electrons will either be attracted or repelled, depending on the charge of the electron and the direction of the electric field. Positively charged electrons will move towards the direction of the electric field, while negatively charged electrons will move in the opposite direction.

3. What happens to electrons in a magnetic field?

When an electron enters a magnetic field, it will experience a force perpendicular to its velocity and the magnetic field. This force causes the electron to move in a circular or helical path, depending on the strength of the magnetic field and the velocity of the electron.

4. Can magnetic fields change the energy of electrons?

Yes, magnetic fields can change the energy of electrons through a process called magnetic induction. When an electron moves through a changing magnetic field, it will experience a change in its kinetic energy, which can result in the emission of photons or the induction of an electric current.

5. How do magnetic and electric fields interact with each other?

Magnetic and electric fields are closely related and can interact with each other. When an electron moves through a magnetic field, it will create an electric field. Similarly, when an electric current flows through a wire, it will create a magnetic field around the wire. This interaction is the basis for many technological applications, such as electric motors and generators.

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