of 1 Hz. The arrows, left or right, change the frequency step size. Watch the string carefully as you change the frequency. At some frequency, you will see the string resonate and oscillate in the fundamental mode. Carefully adjust the frequency until the amplitude observed is the biggest. Record the data in a chart in your notebook similar to the one shown below: Figure 6 3. Higher Modes To find the other modes, keep watching the string as you increase the frequency of the driver. When you think you have reached a higher mode, record the frequency in your chart and see if it agrees with your prediction. Count the number of nodes for each mode. Try to find the first five or six modes. For a long string, some students find as many as ten nodes. Number the modes and record their frequencies. For each mode, sketch the shape of the string. What regularity in frequency did you observe from one mode to the next? Are the mode frequencies multiples of the fundamental frequency, as you were told in lecture? Note that the simple formula that says all modes of a string are exact multiples of the fundamental frequency is not quite correct for a string that has some stiffness to it. 4. The “Plucking Game” For these questions, just try to work out the answers on the basis of what you know about the different modes (theoretical) — it will be difficult to verify them experimentally with the string you have in the set-up. If you pluck the string at the center, what are the modes that will be excited? What modes will be excited when you pluck the string: at 1/3 the distance? at 1/5 the distance?
of 1 Hz. The arrows, left or right, change the frequency step size. Watch the string carefully as you change the frequency. At some frequency, you will see the string resonate and oscillate in the fundamental mode. Carefully adjust the frequency until the amplitude observed is the biggest. Record the data in a chart in your notebook similar to the one shown below: Figure 6 3. Higher Modes To find the other modes, keep watching the string as you increase the frequency of the driver. When you think you have reached a higher mode, record the frequency in your chart and see if it agrees with your prediction. Count the number of nodes for each mode. Try to find the first five or six modes. For a long string, some students find as many as ten nodes. Number the modes and record their frequencies. For each mode, sketch the shape of the string. What regularity in frequency did you observe from one mode to the next? Are the mode frequencies multiples of the fundamental frequency, as you were told in lecture? Note that the simple formula that says all modes of a string are exact multiples of the fundamental frequency is not quite correct for a string that has some stiffness to it. 4. The “Plucking Game” For these questions, just try to work out the answers on the basis of what you know about the different modes (theoretical) — it will be difficult to verify them experimentally with the string you have in the set-up. If you pluck the string at the center, what are the modes that will be excited? What modes will be excited when you pluck the string: at 1/3 the distance? at 1/5 the distance?