I want to know if wave length or frequency will change when a wave move from a string of a certain linear density to another of a different linear density?
When you say it moves to the other string, do you mean vibrations in the second arising because of the movement of the first? Or are you merely replacing one string with another and applying the same stimulus?
OK, so it's a traveling wave. That means some source is generating the wave at one end. Where the wave hits the boundary, what will the frequency be at that point? How will that relate to the frequency each side?