Question 1: Define the motor effect and explain how it is used in a loudspeaker.

Answer: The motor effect is the force exerted on a current-carrying conductor placed within a magnetic field, causing motion. In a loudspeaker, this effect causes the cone to move back and forth, producing sound waves.

Question 2: Describe the role of the permanent magnet and the coil in a loudspeaker.

Answer: The permanent magnet creates a magnetic field, while the coil carries an electric current. The interaction between the magnetic field and the current causes the coil and cone to vibrate, producing sound.

Question 1: A coil in a loudspeaker carries a current of 2.5 A and experiences a magnetic force of 0.05 N when placed in a magnetic field of 0.2 T. Calculate the length of the wire within the magnetic field. Use the formula F = BIL, where F is force, B is magnetic flux density, I is current, and L is length.

Answer: L = F / (B * I) = 0.05 / (0.2 * 2.5) = 0.05 / 0.5 = 0.1 meters

Question 2: If the voltage applied to the loudspeaker coil is 12 V and the resistance of the coil is 6 Ω, calculate the current flowing through the coil using Ohm's law.

Answer: I = V / R = 12 / 6 = 2 A

Question 1: Describe a simple experiment to demonstrate the motor effect using a wire, a magnet, and a power supply. Include the variables that need to be controlled.

Answer: Connect a straight wire to a power supply and place it within a magnetic field created by a permanent magnet. When current flows through the wire, it will experience a force and move. Variables to control include current magnitude, magnetic field strength, and wire position.

Question 2: List three safety precautions students should observe when conducting experiments involving electrical currents and magnets.

Answer: Ensure power supplies are turned off when setting up, avoid contact with live wires, and keep magnetic objects away from electronic devices to prevent damage.

Question 1: A test shows that increasing the current in a loudspeaker coil from 1.5 A to 3.0 A doubles the amplitude of the cone's vibration. Explain how the motor effect contributes to this observation.

Answer: The motor effect produces a force proportional to the current. Doubling the current doubles the force on the coil, increasing the cone's vibration amplitude and producing louder sound.

Question 2: In an experiment, a loudspeaker's coil is subjected to a magnetic field of 0.3 T. When a current of 2 A flows through the coil, the force exerted on a 0.2 m length of wire is measured as 0.12 N. Is this consistent with the formula F = BIL? Show your calculation.

Answer: F = BIL = 0.3 * 2 * 0.2 = 0.12 N, which matches the measured force, so the data is consistent.

Question 1: Explain how the motor effect is utilised in modern wireless loudspeakers and the advantages it provides.

Answer: The motor effect drives the cone movement in wireless loudspeakers by applying electrical signals to the coil within a magnetic field, enabling wireless audio transmission and clearer sound with less distortion.

Question 2: Suggest one technological improvement that could enhance the performance of loudspeakers based on the principles of the motor effect.

Answer: Using stronger permanent magnets and lightweight materials for the cone can increase force and improve sound quality.