Transverse vs Longitudinal
Which type of wave moves the medium perpendicular to the direction the wave travels?
Transverse Wave
What symbol is commonly used for wavelength?
Wavelength is λ.
What kind of wave is sound (transverse or longitudinal)?
Sound is a longitudinal wave.
What do the letters in "RADAR" stand for (basic idea: detection by radio waves)?
RADAR: Radio Detection And Ranging (basic idea).
Which type of wave requires a material medium and consists of compressions and rarefactions?
Mechanical Longitudinal Waves
What is the unit for frequency?
Frequency unit is hertz (Hz).
What is an echo in simple terms?
An echo is the reflection of sound that arrives at the listener after bouncing off a surface.
What is SONAR commonly used for? Give one example.
SONAR is used for underwater detection, e.g., locating submarines or mapping the seafloor.
Give one real life example of a transverse wave and one example of a longitudinal wave (one sentence each).
Transverse Wave: Light waves or waves on a string.
Longitudinal Wave: Sound Waves in air or compressions in a slinky.
If a wave has a period of 0.02 seconds, what is its frequency? (show the calculation)
Period T=0.02 s
T=0.02 s
so frequency ƒ=1/T=1/0.02=50 Hz
Does sound travel faster in air or in water? Answer and give a short reason.
Sound travels faster in water than in air because particles in water are closer together, allowing faster transmission of vibrations.
How is ultrasound used in medicine? Give one common application.
Ultrasound in medicine: imaging internal organs or fetuses (sonography).
Explain in one short sentence why light is a transverse wave and why sound in air is longitudinal.
Light is transverse because its oscillations are perpendicular to propagation; sound in air is longitudinal because air molecules oscillate back and forth in the direction the sound travels.
Write the formula that relates wave speed v, frequency ƒ, and wavelength λ.
Formula: v=ƒ λ
The speed of sound in air at room temperature is about 343 m/s. How long does sound take to travel 686 m? (show the calculation)
Time = distance / speed:
t=686 m/343 m/s =2.0 s
Explain briefly how radar uses electromagnetic waves to detect objects (one or two sentences).
Radar sends out radio (EM) pulses; when pulses reflect off an object and return, the system measures the return time to determine distance and often direction.
A string vibrates left and right while a pulse travels along it to the right. Identify the wave type and briefly justify your answer.
Wave type: Transverse (string vibrating perpendicular to direction of travel). Justification: medium displacement is perpendicular to wave travel.
A wave has wavelength λ=0.5 m and frequency ƒ=4 Hz. Calculate the wave speed v and show your work.
v=ƒλ =4 Hz×0.5 m =2 m/s
A tuning fork causes a sound at 512 Hz. If the speed of sound in air is 343 m/s, calculate the wavelength of this sound. Show your calculation using the formula v=ƒλ.
Wavelength: λ=vƒ=343 m/s512 Hz≈0.67 m (approximate: 0.6699 m).
Sonar sends out pulses and measures the time for echoes to return. If a sonar ping returns after 2.0 s and the speed of sound in seawater is 1500 m/s, how far away is the object? (Show calculation and remember the ping travels to the object and back.)
Sonar distance: ping time is round-trip 2.0 s so one-way time is 1.0 s.
Distance = speed × time = 1500 m/s × 1.0 s = 1500 m