# Will the wavelength decrease when the wave moves from a light string to a heavy

hi, i was just wondering if a wave's wavelength will change when it goes from a light string to a heavier one. I think it wouldn't affect it, however I know that velocity will be affected as the linear density will be changed. But am I right, will the wavelength remain unaffected?

## Answers and Replies

Related Introductory Physics Homework Help News on Phys.org
Tom Mattson
Staff Emeritus
Gold Member
You're right that the speed changes. It seems that the essential piece of information that you are missing is this: the frequency does not change.

So since you know that $v_1=\lambda_1f_1$ and $v_2=\lambda_2f_2$, so what can you say about the wavelengths?

ok, so that means that although the mass of the string increases, this will have no affect whatsoever on the frequency because since
v= sqrt(T/linear density) and also (wavelength/tension)
and increasing the mass of the string will have no affect on the tension, v increases as the tension remains constant, therefore will the wavelength have to INCREASE in order to compensate the equation? Am i on the right track?

Tom Mattson
Staff Emeritus
Gold Member
insertnamehere said:
v= sqrt(T/linear density) and also (wavelength/tension)
The first part is right, but the second part is not. v does not equal (wavelength/tension). That expression doesn't even have the right units to be a speed.

and increasing the mass of the string will have no affect on the tension, v increases as the tension remains constant, therefore will the wavelength have to INCREASE in order to compensate the equation? Am i on the right track?
The wave speed decreases as you move to the string of higher mass density.

oh no, i meant v= (wavelength/PERIOD)