VISUAL PHYSICS ONLINE

3.1 WAVES

P31 011

You play a single note on a guitar. How do you play another note on the instrument which produces:

(A)

A louder sound?

(B)

A higher pitch note?

View solution below only after you have completed answering the question. The solution is not in a form that you would answer in an examination. The answers are often in more detail to help improve your appreciation and understanding of the physics.

Solution

Knowledge string instruments

Visualise the problem (image a picture of a guitar). Often knowing the equation applicable to the situation can help you answer a question.

(A)

A louder sound is produced by creating a wave of larger amplitude by giving the string a greater displacement by plucking it more vigorously.

(B)

Pitch relates to the frequency of the sound. A wave of greater frequency can be produced by:

(1) Exciting a shorter length L of the string.

(2) Plucking a string which has a smaller linear density (usually a less thick string).

(3) Increasing the tension of the string with the tuning knob.

(4) Plucking the string in such a way as to excite the higher harmonics (greater n value).