Chapter 23, Problem 19P

Review. After removing one string while restringing his acoustic guitar, a student is distracted by a video game. His experimentalist roommate notices his inattention and attaches one end of the string, of linear density μ = 3.00 × 10⁻³ kg/m, to a rigid support. The other end passes over a pulley, a distance, ℓ = 64.0 cm from the fixed end, and an object of mass m = 27.2 kg is attached to the hanging end of the string. The roommate places a magnet across the string as shown in Figure P23.19. The magnet does not touch the string, but produces a uniform field of 4.50 mT over a 2.00-cm length of the string and negligible field elsewhere. Strumming the string sets it vibrating vertically at its fundamental (lowest) frequency. The section of the string in the magnetic field moves perpendicular to the field with a uniform amplitude of 1.50 cm. Find (a) the frequency and (b) the amplitude of the emf induced between the ends of the string.