Electromagnets and conservation of energy

Click For Summary
SUMMARY

The discussion centers on the energy dynamics of two bar electromagnets when activated and deactivated. When the electromagnets are turned on and pulled apart, energy is input into the system, which dissipates primarily as heat and electromagnetic radiation. Lenz's law explains that when the current is turned off, the magnetic field attempts to maintain itself, resulting in energy being returned to the circuit but ultimately lost as heat due to ohmic losses. The work done in separating the magnets also contributes to energy loss, converting kinetic energy into heat through friction.

PREREQUISITES
  • Understanding of Lenz's Law in electromagnetism
  • Knowledge of electromagnetic radiation principles
  • Familiarity with ohmic losses in electrical circuits
  • Basic concepts of kinetic energy and work in physics
NEXT STEPS
  • Study Lenz's Law and its applications in electromagnetism
  • Research the principles of electromagnetic radiation and its effects
  • Explore methods to minimize ohmic losses in electrical circuits
  • Investigate the relationship between kinetic energy and work in mechanical systems
USEFUL FOR

Physics students, electrical engineers, and anyone interested in the principles of electromagnetism and energy conservation in electrical systems.

abccbaabc014
Messages
7
Reaction score
0
Right, I'll try to get this question across.
Say you have 2 bar electromagnets, aligned so when you turn them on they are attracted to each other. You start with them touching, turn them on and pull them apart. You then turn of the current and put them back together. If you continue to repeat this, you are putting a lot of energy in, but where does it go? The only two answers I can think of are heat and EM radiation.
 
Physics news on Phys.org
Some of the energy also gets dumped back into the circuit when you turn off the electricity. Lenz's law will tell you that when you turn off the current that is supporting the magnetic field, then the field will try to keep a current to support itself. Some of the field's energy gets dumped back into the electromagnet in order to sustain itself and this gets dissipated as heat through ohmic losses. The changing magnetic fields and currents when you turn on and off the magnets will produce a small amount of electromagnetic radiation. The one you miss is the work done in separating the magnets. The magnets repulse each other over a distance producing work, this energy comes out of the magnetic fields (which is replenished by the currents in the electromagnet). The resulting kinetic energy is expended as heat due to friction.

So yes, in the end you eventually end up with waste heat and some EM radiation but the energy goes through various transfers until that point.
 

Similar threads

  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 21 ·
Replies
21
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 16 ·
Replies
16
Views
3K
  • · Replies 16 ·
Replies
16
Views
5K
  • · Replies 2 ·
Replies
2
Views
2K