Stationary wavesEdexcel International A Level Physics: Mind map

Exam questions on Stationary waves

1. A student fixes one end of a long elastic cord to a wall and shakes the other end up and down. At one particular frequency a stationary wave appears on the cord, with the cord appearing still at certain points and vibrating with large amplitude at others.
   Explain how the stationary wave is formed on the cord.2 marks
2. A guitar string of length 0.60 m and mass per unit length 4.0 × 10⁻⁴ kg m⁻¹ is fixed at both ends. It is held under a tension of 36 N and plucked so that it vibrates in its fundamental mode (one antinode).
   The guitarist tightens the string until the tension is 64 N. Calculate the new frequency of the fundamental mode.2 marks
3. In Core Practical 5 a student investigates a string of length 0.80 m and mass per unit length 1.5 × 10⁻³ kg m⁻¹. One end is attached to a vibration generator connected to a signal generator. The string passes over a pulley, and a hanging mass at the other end provides the tension. The student takes g = 9.81 N kg⁻¹.
   Describe how the student can find the frequency of the fundamental stationary wave on the string.3 marks