Physics 9702 · AS & A Level · Stationary waves

Stationary waves — practice question

Fig. 5.1 depicts a string under tension between two fixed points P and Q. A vibrator is fitted close to end P of the string, and end Q is attached to a wall. The vibrator oscillates at a frequency of $50\,\text{Hz}$ and generates a transverse wave that moves along the string at a speed of $40\,\text{m s}^{-1}$.
(a(i))[2]

Calculate the wavelength of the transverse wave travelling on the string.

(a(ii))[2]

Explain how this arrangement may create a stationary wave on the string.

(b(i))[2]

On Fig. 5.2, mark every node with the letter N and every antinode with the letter A.

(b(ii))[1]

Use your answer in (a)(i) to calculate the length of the string PQ.

(b(iii))[3]

On Fig. 5.2, sketch the stationary wave at time $(t + 5.0\,\text{ms})$. Explain your answer.

(c(ii))[1]

Use your answer in (a)(i) to work out the length of string PQ.

(c(iii))[3]

On Fig. 5.2, sketch the stationary wave at time $(t + 5.0\,\text{ms})$. Explain your answer.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct use of $v=f\lambda$

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