8500 Hz and Longitudinal
Speed = frequency x wavelength
Speed of sound at 20 degrees Celsius is approximately 340 m/s
Answer: 
Explanation:
Given
Current in the first wire 
Current in the second wire 
wires are
apart
Force per unit length between the current-carrying wires is

Force exerted by the wires is the same
Put the values

This force will be repulsive in nature as the current is flowing opposite