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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.
Additional Information
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.
Science Standards
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.
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Waves, including
sound and seismic waves, waves on water, and light waves, have
energy and can transfer energy when they interact with matter.
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Describe the
motion of pendulums and vibrating objects.
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Describe the
behavior of waves when they interact.
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Explain how
energy is stored and transformed in vibrating and oscillating
objects.
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