Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Waves transfer energy from one place to another without the transfer of matter.
Transverse waves (e.g., light) oscillate at right angles () to the direction of energy transfer, consisting of crests and troughs.
Longitudinal waves (e.g., sound) oscillate parallel to the direction of energy transfer, consisting of compressions and rarefactions.
The Amplitude () is the maximum displacement from the equilibrium position; it determines the loudness of sound and brightness of light.
Wavelength () is the distance between two successive identical points on a wave (e.g., crest to crest).
Frequency () is the number of waves passing a point per second, measured in Hertz (). For sound, frequency determines pitch.
Sound requires a medium (solid, liquid, or gas) to travel and cannot travel through a vacuum.
Light is an electromagnetic wave that travels at approximately in a vacuum and can travel through empty space.
Law of Reflection: The angle of incidence () is equal to the angle of reflection ().
Refraction occurs when a wave changes speed as it enters a medium of different optical density, causing it to bend.
📐Formulae
💡Examples
Problem 1:
Calculate the speed of a sound wave that has a frequency of and a wavelength of .
Solution:
Explanation:
By applying the wave equation , we multiply the frequency by the wavelength to determine the wave speed.
Problem 2:
A wave takes to complete one full cycle. What is its frequency?
Solution:
Explanation:
Frequency is the reciprocal of the period (). Using gives the number of cycles per second.
Problem 3:
If a lightning strike is seen and the thunder is heard later, how far away is the storm? (Assume speed of sound )
Solution:
Explanation:
Since light travels much faster than sound, we assume the light reaches the observer almost instantly. The distance is found by multiplying the speed of sound by the time delay.