Chapter 3- Waves: Investigating Resonance

Question 1

Give a brief description of how to investigate resonant frequencies.

Answer 1

Measure the mass and length of different strings. (Find the mass per unit length)(kgm^-1). Set up the equipment. Turn on the signal generator and vary the frequency the vibration transducer vibrates.
Find the first harmonic.
Investigate how each variable affects the first harmonic.

Question 2

What variables can you change to investigate resonant frequency? (3)

Answer 2

Move the vibration transducer to change l.
Add masses to change the tension.
Use a range of string samples to vary mass per unit length.

Question 3

How do you calculate mass per unit length?

Answer 3

M (mass of string) / L (length of string) (kg/m)

Question 4

How do you measure the tension on the string?

Answer 4

T (N) = m (kg) x g (m/s^2) = mass x acceleration due to gravity

Question 5

How does increasing the length of the string affect resonant frequency?

Answer 5

Longer the string = lower the resonant frequency

Half wavelength longer. So lambda increases and f decreases.

Question 6

How does increasing the mass per unit length of the string affect the resonant frequency?

Answer 6

Heavier string = lower resonant frequency

The waves travel more slowly down the string. Lower