its contains a permanent magnet.
sound signal converted to varying current signal enters the speech coil.
the current in the speech coil creates a magnetic force on the coil.
the magnetic force on the speech coil is uni-directional.
Explanation
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The correct answer is D. the magnetic force on the speech coil is uni-directional.
Explanation: In a loudspeaker, the current in
the speech coil creates a magnetic force on the coil, which interacts with the permanent magnet to move the coil and produce sound. This magnetic force is not unidirectional but rather changes direction based on the direction of the current flow in the coil.
The correct answer is:
D. the magnetic force on the speech coil is uni-directional
Explanation:
A loudspeaker works based on the interaction between a permanent magnet and an electromagnetic coil (speech coil) that carries a varying current signal.
(A) Correct: A loudspeaker contains a permanent magnet to create a stable magnetic field.
(B) Correct: The sound signal is converted into an alternating current (AC) signal, which flows through the speech coil.
(C) Correct: The varying current in the speech coil creates a changing magnetic force due to electromagnetic induction, causing the coil to move.
(D) Incorrect: The magnetic force is not uni-directional; it alternates direction as the current in the coil changes direction. This back-and-forth movement vibrates the diaphragm, producing sound waves.
Thus, option D is the incorrect statement.
please can you review?
🧠 Memory Hack – "P.I.C.K."
P – Permanent Magnet: Fixed, always there.
I – Input Current (from music/audio signal).
C – Coil vibrates with changing current.
K – Kinetic Motion = vibration = sound.
Important Twist:
Because the current alternates, the magnetic force reverses, and that’s what makes the coil and cone vibrate back and forth — producing sound waves!
So the force is not uni-directional (and that’s why option D is wrong).
