Stationary wavesEdexcel International A Level Physics: Flashcards

What these 13 flashcards ask

What is a stationary wave?
What is a node?
What is an antinode?
How far apart are adjacent nodes?
How is a stationary wave usually formed on a string?
What condition must be met for a stationary wave on a string fixed at both ends?
What is the wavelength of the fundamental on a string of length L?
State the equation for the speed of a wave on a string.
What does μ mean in v = √(T/μ)?
Write the fundamental frequency of a string in terms of T, μ and L.
What happens to the fundamental frequency if the tension is quadrupled?
How can you tell when a vibrating string is in its fundamental mode?
In Core Practical 5, how is the tension in the string provided and calculated?

Exam questions on Stationary waves

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
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
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

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).