Physics* - Waves & Sound Review

How are frequency and period related?

Frequency and period really measure the same thing: how quickly oscillations are occurring. Frequency and period are reciprocals of each other. If "f" is the frequency and "T" is the period, then f=1/T and T=1/f

How are loudness and amplitude related?

Loudness is the brain's perception of the amplitude of a sound wave. Amplitude is about the wave; loudness is about how your brain 'hears' the amplitude of a wave.

How are pitch and frequency related?

Pitch is the brain's perception of the frequency of a sound wave. Frequency is about the wave; pitch is about how your brain 'hears' different frequencies.

True or False: A wave doesn't cause matter to move from place to place, only energy.

TRUE. When a wave passes, the particles or molecules move a short distance but return to their starting point. Only the energy travels through the medium.

Why does the loudness of a sound decrease as you get farther from the source of the sound?

The amplitude of any wave decreases as it travels through the medium because of friction and the energy being dissipated. For sound, the amplitude (loudness) decreases with distance.

What is the amplitude of a wave?

The biggest change in the medium as the wave passes. In the diagram abov, the red lines measure the amplitude.

What is the difference between longitudinal waves and transverse waves? Give an example of each type.

The difference is in how the particles move in the medium. In a longitudinal wave the medium moves in the same direction as the energy. Sound waves in air are longitudinal waves. In a transverse wave the medium moves at right angles to the direction of the energy. Water waves or waves in a slinky are transverse.

What is the main function of our ears?

The ear's main function is to detect sound waves in the air and convert them to nerve impulses that are transmitted to the brain.

What is the frequency of a wave?

The frequency of a wave is the number of waves that occur every second.

What do we mean by the "resonant frequency" of an object? Is it the same as 'fundamental frequency'?

The frequency that an object vibrates at naturally when disturbed is the resonant frequency. It's the same as the fundamental frequency of a standing wave.

What causes sounds to have different tones or 'colors', even when the pitch is the same?

The mix of frequencies, or the spectrum, of a sound creates what our brain perceives as tone or color. This is why a clarinet and a guitar don't sound the same, even when they play the same pitch.

What is the period of a wave?

The period is the amount of time required for one complete cycle or oscillation.

How can very loud sounds damage our ability to hear?

The very large air pressure of a loud sound can damage the eardrum or the small bones in the middle ear.

What is the wavelength of a wave?

Wavelength is the distance between peaks of a moving wave. The picture above shows red lines that are both equal to the wavelength.

A __________________________ can occur when an object is made to vibrate at its natural frequency. When this happens, the wave seems to be motionless.

standing wave

The distance a wave travels during one complete cycle is the ___________ . What units should be used?

wavelength meters

Describe the difference between a musical sound and a noise.

A musical sound contains a few frequencies that are related to each other. The most important frequency is what we hear as the pitch. A noise contains a lot of frequencies that are not related to each other. There is no definite pitch to a noise.

Explain the difference between a musical sound and a noise.

A musical sound contains only a few frequencies that are multiples of the fundamental. A noise contains many frequencies with no clear relation between them. Also, a musical sound will have a well defined pitch; noises do not have a well-defined pitch.

What is a 'standing wave'? Describe briefly how a standing wave can form.

A standing wave occurs when the energy is put into the medium at a frequency that matches the resonant frequency of the medium. The waves traveling in the medium meet and add together to increase the amplitude of the wave. Nodes or stationary points occur where the waves cancel each other out.

Normally, ____________ is the medium for sound waves.

air

When you increase the volume on your music player, you are increasing the ________________ of the sound waves.

amplitude

The only type of wave that doesn't need a medium to travel through.

electromagnetic waves

A musician plays different pitches on an instrument by changing the ________________ of the sounds.

frequency

Our ears and brain interpret the amplitude of a sound wave as __________________________.

loudness (or intensity).

The material the wave moves through is called the ___________________________.

medium.