19. You are standing at the beach and watching waves lap against the shore. Every 3.5 s a new wave arrives. What is the frequency for these waves? Justify your choice with mathematics. a. 0.29 Hz b. 3.5 Hz c. 0.35 H: d. 29 Hz 20. What is the primary voltage in a transformer that has 300 turns of wire in the secondary coil and 450 turns in the primary coil, if the secondary voltage is 66.0 V? Justify your choice with mathematics a. 44 V b. 165 V c. 120 V ti. 99 V