Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Sound is created by vibrations. These vibrations travel through mediums (solids, liquids, or gases) as sound waves.
Volume is how loud or quiet a sound is. It is determined by the strength or size of the vibration, known as amplitude.
A larger vibration produces a louder sound ( - decibels), while a smaller vibration produces a quieter sound.
Pitch is how high or low a sound is. It is determined by how fast an object vibrates, known as frequency.
High-frequency vibrations (fast) create a high pitch, while low-frequency vibrations (slow) create a low pitch ( - Hertz).
To change pitch on a string instrument: shorter, thinner, or tighter strings vibrate faster and produce a higher pitch.
Light travels in straight lines. When light hits an object, it can be reflected (bounce off), refracted (bend), or absorbed.
📐Formulae
💡Examples
Problem 1:
A student blows into a long straw and then cuts the straw to make it shorter. What happens to the pitch of the sound?
Solution:
The pitch becomes higher.
Explanation:
Shorter columns of air vibrate faster than longer ones. Because the vibrations are faster, the frequency increases, resulting in a higher pitch.
Problem 2:
If you pluck a guitar string very hard, which property of sound are you changing: Pitch or Volume?
Solution:
Volume.
Explanation:
Plucking a string harder increases the amplitude of the vibration. A larger amplitude carries more energy, making the sound louder ().
Problem 3:
Identify the unit used to measure the frequency of a sound wave.
Solution:
(Hertz).
Explanation:
Frequency is the number of cycles per second, and in the metric system, this is represented by the unit .