Standing Waves on a String 17 3 points In the figure, a string with length L and mass m, is tied to a sinusoidal oscillator Which of the following change will set up the second harmonic on the string? at P; the string is running over a support at Q and stretched by a block of mass my. The amplitude of the motion at P is small enough for that point to be a. halve the frequency if: leave I, m., and my unchanged considered a node. A node also exists at Q. The fourth harmonic is set up on the b. halve the block's mass ma and double the string's length _; string when the oscillator frequency is f- leave my and f unchanged Oscillator c. halve the string's mass m, and the block's mass mg; leave D and f unchanged d. quadruple the block's mass mB leave L. m., and f unchanged b and c only MB O c and d only a and d only a, b, and d only a and b only