Lab 23B _ Harmonic Motion

What is the primary function of the "wiggler" in this experiment?

• To measure the string's length.

• To generate sound waves.

• To vibrate the string.

• To display the frequency.

What is a harmonic in the context of a vibrating string?

• Any random frequency applied to the string.

• A specific frequency that creates a standing wave.

• The maximum displacement of the string from its equilibrium position.

• The length of one complete wave on the string.

Answer explanation

A harmonic is the natural frequency of a wave that establishes a clear wave pattern that appears not to move. This is called a standing wave.

If the string length is 1 meter and the string is vibrating at its first harmonic, what is the wavelength?

• 0.5 meters

• 1 meter

• 2 meters

• 4 meters

Answer explanation

In order to find the wavelength of a standing wave, you must measure 2 segments. In this case, Mr. Palus measured one segment and then must multiply by 2 to get the wavelength.

Why did Mr. Palus stop adjusting the frequency when the wiggler went quiet?

Answer explanation

When the noise level drops, the string is vibrating at or near its harmonic frequency. You will also see clear nodes forming on the string.

What is the wavelength of the first harmonic?

• 1 meter

• 0.5 meters

• 2 meters

• 1.5 meters

What is the amplitude of this plucked string?

Answer explanation

The amplitude is half of the distance between points A and C. In this case, you would take 10 cm and divide by 2 to get the correct answer of 5 cm.
You may have received half credit if you did not include units (cm).

If the distance from the top of the string to the node is 50 cm, what is the wavelength?

• 75 cm
• 150 cm
• 100 cm
• 25 cm

Answer explanation

Mr. Palus measured one segment of the harmonic. In order to find the wavelength, you need 2 segments. 50 cm x 2 = 100 cm or 1 meter.

What is the wavelength of the 4th harmonic if the string length is 1 meter?

• 0.25 m

• 0.50 m

• 0.75 m

• 1.00 m

What is the amplitude of the 5th harmonic?

• 0.8 cm

• 0.4 cm

• 0.5 cm

• 0.7 cm

How well do you think you understand Harmonics?

• I'm confused

• I'm sort of confused

• I understand some parts

• I understand most parts

• I understand everything.