Because the string is driven from one end, each successive mass in the row will start later than the one before it (in other words each mass is slightly out of phase with its neighbor). So the masses ...Because the string is driven from one end, each successive mass in the row will start later than the one before it (in other words each mass is slightly out of phase with its neighbor). So the masses that make up the wave on the string will have the largest amplitude only when driven at resonance. What is the period of the wave? (Use the step button and the time to find the period.) What is the frequency of the wave?