Working Principle of Moving Coil Loudspeaker | New Topic [2024]

In this note, we are going to learn about the Working Principle of Moving Coil Loudspeaker. Welcome to Poly Notes Hub, a leading destination for Polytechnic Notes for Diploma Engineering Students.

Author Name: Arun Paul.

About Working Principle of Moving Coil Loudspeaker

Similar to how a motor functions, the moving coil loudspeaker operates on the interaction of a magnetic field and electricity. A voice coil is a coil that is submerged in a steady magnetic field. A force acts on the movable coil as a result of an interaction between the magnetic field and the current as the audio current flows through the voice coil. Due to the force’s proportionality to the audio current, the coil experiences vibratory motion, which in turn causes a conical paper diaphragm to vibrate and alter air pressure, producing sound waves.

Given the current flowing through the coil and the magnetic field, the force acting on it is as follows:

F = B.i.l.sinα

Where,

• F = force in Newton,
• B = Flux density in Tesla,
• i = Flowing current in Amperes,
• l = Length of the coil in meter,
• α = angle between the coil and the field
  Normally, α = 90°, and hence

F = B.i.l (as sin90 = 1)

The coil will stay inside the uniform flux density area when its velocity is minimal. Thus, the output is linear for modest coil motion. Electromagnetic induction causes a reverse EMF when the coil travels in a magnetic field. The coil’s motion becomes stable as a result.