Question 1: Define the motor effect in the context of loudspeakers.

Answer: The motor effect is the force exerted on a current-carrying conductor placed in a magnetic field, which causes movement.

Question 2: Explain how the motor effect is utilised in a loudspeaker to produce sound.

Answer: An electrical audio signal causes a current in the coil, which interacts with a magnetic field, producing a force that moves the coil and cone, generating sound waves.

Question 1: Describe the role of the permanent magnet and coil in a loudspeaker.

Answer: The permanent magnet creates a magnetic field, and the coil carries the audio signal current; their interaction causes the coil to move, producing sound.

Question 2: What determines the direction of the coil's movement in a loudspeaker?

Answer: The direction of the current in the coil determines the direction of the force and movement, according to Fleming's Left-Hand Rule.

Question 1: A coil in a loudspeaker has a length of 0.05 m and carries a current of 2 A in a magnetic field of 0.1 T. Calculate the force on the coil.

Answer: Force = BIL sin θ (assuming θ = 90°), so Force = 0.1 T × 0.05 m × 2 A × 1 = 0.01 N.

Question 2: If the coil moves 1 mm in response to the force calculated above, what is the approximate work done in moving the coil?

Answer: Work = Force × Distance = 0.01 N × 0.001 m = 0.00001 Joules.

Question 1: Outline a basic experiment to demonstrate the motor effect using a coil, a magnet, and a power supply. Include variables to control and safety precautions.

Answer: Set up a coil of wire in a magnetic field created by a permanent magnet connected to a power supply. Vary the current or magnetic field strength and observe the movement of the coil. Control variables such as the current magnitude and coil position. Ensure safety by handling electrical connections carefully and avoiding short circuits.

Question 1: A loudspeaker coil is placed in a magnetic field of 0.2 T and carries a current of 3 A. If the coil experiences a force of 0.06 N, what is the length of the coil?

Answer: Using F = BIL, L = F / (B × I) = 0.06 N / (0.2 T × 3 A) = 0.1 m.

Question 2: Explain how the frequency of the audio signal affects the movement of the coil and the sound produced.

Answer: Higher frequency signals cause the coil to oscillate more rapidly, producing higher-pitched sounds; lower frequencies result in slower oscillations and lower pitches.

Question 1: Describe how loudspeakers use the motor effect to convert electrical signals into sound in everyday devices.

Answer: Loudspeakers use an electric audio signal to generate a varying current in a coil within a magnetic field. The resulting force causes the coil and cone to vibrate, producing sound waves.

Question 2: Identify one technological advancement that has improved loudspeaker performance related to the motor effect.

Answer: The development of stronger magnets and lightweight cone materials has improved sound quality and efficiency of loudspeakers.