Calculating wavelength
wave velocity \$v_c=\dfrac{c}{\sqrt{\epsilon}}\$  thus

\$\lambda(f)=\dfrac{c}{\sqrt{\epsilon}f}\$

When f &lt; 10% \$\lambda\$, the rise time is limited by RC time constant of cable C (100pF/m typ.) and total R = Rs+Rload (neglecting cable loss)