Question 1: Define the motor effect in physics.

Answer: The motor effect is the force experienced by a current-carrying conductor placed within a magnetic field, causing it to move.

Question 2: Describe how a loudspeaker uses the motor effect to produce sound.

Answer: A loudspeaker uses a coil of wire within a magnetic field; when an audio signal current flows through the coil, it experiences a force that moves it back and forth, creating vibrations in a cone that produce sound waves.

Question 3: Explain why the coil in a loudspeaker moves in response to an audio signal.

Answer: Because the current in the coil interacts with the magnetic field, generating a force that causes the coil to move, thus producing vibrations.

Question 1: A coil in a loudspeaker has a resistance of 8 Ω and carries a current of 0.5 A when producing sound. Calculate the power dissipated in the coil. Use the formula P = I²R.

Answer: P = (0.5)^2 × 8 = 0.25 × 8 = 2 W

Question 2: If the magnetic flux density in a loudspeaker's magnetic field is 0.1 T, and the length of the wire in the magnetic field is 0.2 m, calculate the force on a wire carrying a current of 0.5 A. Use F = BIL, where I is current, B is magnetic flux density, and L is length.

Answer: F = 0.1 T × 0.5 A × 0.2 m = 0.01 N

Question 1: Identify three variables that affect the loudness of sound produced by a loudspeaker.

Answer: The current in the coil, the strength of the magnetic field, and the frequency of the audio signal.

Question 2: Outline safety precautions that should be taken when conducting experiments involving loudspeakers and electrical currents.

Answer: Ensure all electrical connections are insulated, avoid touching live wires, keep the workspace dry, and operate equipment within recommended voltage and current limits.

Question 1: A loudspeaker's coil has a resistance of 6 Ω and carries a current of 0.4 A when producing sound. Describe what happens to the coil and the sound produced if the current increases to 0.6 A.

Answer: The coil experiences a greater force, causing it to move more vigorously, which increases the amplitude of vibrations and results in louder sound.

Question 2: Discuss how improvements in magnetic materials can enhance loudspeaker performance.

Answer: Using stronger magnetic materials increases the magnetic flux density, which enhances the force on the coil, leading to greater movement, louder sound, and improved efficiency of the loudspeaker.

Question 3: Explain how the motor effect is exploited in modern loudspeaker technology to produce high-fidelity sound.

Answer: Modern loudspeakers utilise the motor effect by passing an alternating current through a coil within a strong magnetic field. The changing current causes the coil to move back and forth in synchrony with the audio signal, producing vibrations in the cone that generate sound waves with high fidelity. Advances in magnetic materials and coil design improve efficiency, frequency response, and sound quality.