Interference & Stationary Waves (Edexcel A Level Physics)

The photograph shows a guitar.

When a guitar string is plucked, a standing wave is created.

Explain how a standing wave is created on the string.

The diagram shows a standing wave on a guitar string.

The oscillating length of the guitar string is 66 cm.

(1)

Wavelength = ....................................................................

tension in guitar string = 88.6 N

mass per unit length of guitar string = 4.47 × 10⁻³ kg m⁻¹

(3)

Frequency = ................................................

One end of the guitar string is wrapped around a cylindrical tuning peg. Turning the peg changes the total length of the string and hence changes the tension in the string. This changes the frequency of vibration of the string.

Calculate the extension required to produce a tension of 93.4 N in the string.

Young modulus of string material = 1.8 × 10⁹ N m⁻²

cross-sectional area of string = 6.6 × 10⁻⁷ m²

(4)

Extension = ...........................................

Explain the effect that tightening the string has on the frequency of the sound produced.

(2)