# Electrodynamics related question

• fluidistic
In summary, the Bremsstrahlung effect is a method of making X-rays by accelerating electrons through a difference of potential and causing them to emit photons as they are decelerated. The emitted radiation has a lower bandwidth and rate compared to regular RF frequencies. The power of the emitted radiation can be calculated using the Larmor formula. Jackson's textbook provides a detailed treatment of such problems.
fluidistic
Gold Member
I've "learned" how to make X-Rays with the Bremsstrahlung effect. That is, we accelerate electrons (that we get by a current passing through a resistance) through a difference of potential and we put a material (generally metallic) so that electrons get "decelerated" very quickly and they emit photons, X-rays.
My question is: when we accelerate the electrons with the difference of potential, don't they radiate photons?

fluidistic said:
I've "learned" how to make X-Rays with the Bremsstrahlung effect. That is, we accelerate electrons (that we get by a current passing through a resistance) through a difference of potential and we put a material (generally metallic) so that electrons get "decelerated" very quickly and they emit photons, X-rays.
My question is: when we accelerate the electrons with the difference of potential, don't they radiate photons?
For regular RF frequencies it is called a radio transmitter antenna. In this case the radio antenna (usually 1/2 or 1/4 wavelength long) radiates a coherent RF wave (photons) with wavelengths of a few centimeters to ~300 meters. Microwave antennas are slightly different in that the radio waves are often emitted directly from waveguides without physical antennas.

Bob S

fluidistic said:
I've "learned" how to make X-Rays with the Bremsstrahlung effect. That is, we accelerate electrons (that we get by a current passing through a resistance) through a difference of potential and we put a material (generally metallic) so that electrons get "decelerated" very quickly and they emit photons, X-rays.
My question is: when we accelerate the electrons with the difference of potential, don't they radiate photons?

Yes, but the bandwidth of the emitted radiation is much lower than X-rays and the rate of emmission is lower due to the much slower acceleration when compared to the braking mechanism. You can actually calculate the power of the emited radiation using the Larmor formula. Jackson gives a detailed treatment of such problems in his textbook.

Ok thank you guys, really awesome explanations. I get it.

Yes, the accelerated electrons do radiate photons, but in the case of creating X-rays using the Bremsstrahlung effect, the radiation from the accelerated electrons is not the primary source of X-rays. Instead, it is the deceleration of the electrons as they interact with the material that produces the majority of the X-rays. This is because the deceleration of the electrons is much more abrupt and therefore produces a higher energy photon compared to the radiation from the acceleration. Additionally, the process of acceleration and deceleration is not perfectly efficient, so some of the energy from the accelerated electrons is lost to heat and other forms of radiation. Overall, the Bremsstrahlung effect is a more efficient and controlled way of producing X-rays compared to relying solely on the radiation from the acceleration of electrons.

## 1. What is electrodynamics?

Electrodynamics is the branch of physics that deals with the study of the relationship between electric and magnetic fields and how they interact with charged particles.

## 2. What are the fundamental equations of electrodynamics?

The fundamental equations of electrodynamics are Maxwell's equations, which describe the behavior of electric and magnetic fields in the presence of charged particles and changing electric and magnetic fields.

## 3. How does electrodynamics relate to electromagnetism?

Electrodynamics is a subset of electromagnetism, which is the study of the relationship between electricity and magnetism. Electrodynamics specifically focuses on the dynamic behavior of electric and magnetic fields.

## 4. What are some real-world applications of electrodynamics?

Some real-world applications of electrodynamics include the design and operation of electronic devices such as computers and cell phones, the generation and distribution of electricity through power grids, and the study of electromagnetic waves and their use in communication and imaging technologies.

## 5. How does electrodynamics contribute to our understanding of the universe?

Electrodynamics plays a crucial role in our understanding of the universe by providing a framework for explaining and predicting the behavior of electromagnetic phenomena, which are fundamental to many natural processes. It also helps us understand the behavior of charged particles in space, such as those found in the solar wind and in stars and galaxies.

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