Related Labs, Activities, and Other CoolStuff
Dramatically demonstrates nodes, anti-nodes, and standing waves!
Our "Singing" Rods make a great addition to your lessons on sound and waves. Just like the Singing Sword of legend, these magical rods will "sing" for you...if you know the secret. Simply hold a rod between your thumb and forefinger at one of the three marked nodes. Place a little of the included special rosin on your other hand. Then rub that hand along the rod from middle to end. A must for explorations of sound and waves, these rods are an easy way to demonstrate longitudinal waves as opposed to transverse waves. They're ideal for teaching about nodes and anti-nodes in standing waves. And they're a great follow-up activity to see if students really understand sound and waves. You get two rods (75cm and 50cm), so you can demonstrate the relationship of pitch to length.
As you stroke, friction creates a standing wave pattern which emits a tone that grows louder with each stroke. The resulting high-pitched ringing is sure to wake up everyone in class. The rod is marked at the quarter and halfway points. Holding it at the halfway point makes that spot a nodal point and creates the first harmonic. Moving your hand to a quarter point forces the second harmonic - and a higher pitch! (These and other experiments are discussed in the included explanation/activity sheet.) A sample activity from the datasheet is given below. Next, while the rod is "singing" in wave pattern B, grasp it at the mark near the opposite end. Since the mark represents the other node in that wave pattern, grasping it there will not stop the vibration. Touching the rod anywhere else will stop the sound.
In using this product, national and states' science education standards are covered. Some examples are provided here. These are representative, however. Check with your state to find the exact standards.
- Waves, including sound and seismic waves, waves on water, and light waves, have energy and can transfer energy when they interact with matter.
- Describe the motion of pendulums and vibrating objects.
- Describe the behavior of waves when they interact.
- Explain how energy is stored and transformed in vibrating and oscillating objects.
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