P.8BC Characteristics of Waves

What property of this wave is represented by the letter G in the diagram?

• Crest

• Compression

• Wavelength

• Amplitude

Answer explanation

The letter G represents the amplitude of the wave, which is the maximum height of the wave from its rest position. Amplitude indicates the energy of the wave, making it the correct choice among the options provided.

Which characteristic is shared by both transverse and longitudinal waves?

• They always require a medium to travel.

• They transfer energy from one place to another.

• They can only travel through solids.

• Their speed is unaffected by the medium.

Answer explanation

Both transverse and longitudinal waves transfer energy from one place to another, which is a fundamental characteristic of all wave types. This distinguishes them from other phenomena that do not involve energy transfer.

Priya is tuning her guitar and notices that when she tightens a string, the sound it makes has a higher pitch. Which characteristic describes the relationship between frequency and wavelength in this situation?

• To fit more waves per second and increase frequency, the wavelength must be shorter.

• To increase the energy of a wave, the wavelength and frequency must be shorter.

• To increase the speed of a wave, you must increase the wavelength.

• The frequency and wavelength are both determined by amplitude.

Answer explanation

When Priya tightens the string, the frequency increases, resulting in a higher pitch. To accommodate more waves per second (higher frequency), the wavelength must be shorter, which is correctly described in the first answer choice.

Which of the following is an example of a longitudinal wave?

• Ultraviolet

• Microwaves

• Sound

• X-rays

Answer explanation

Sound is a longitudinal wave because its particles vibrate parallel to the direction of wave propagation. In contrast, ultraviolet, microwaves, and X-rays are electromagnetic waves, which are transverse.

If the frequency of a wave increases, what happens to its wavelength and energy?

• Wavelength decreases and energy increases.

• Wavelength increases and energy decreases.

• Wavelength and energy both decrease.

• Wavelength and energy both increase.

Answer explanation

As frequency increases, wavelength decreases due to the inverse relationship (speed = frequency x wavelength). Energy increases with frequency, following the equation E = hf, where h is Planck's constant.

Charlotte is trying to listen to music coming from a speaker in another room. She notices that when she puts her ear against the wall, she can hear the music more clearly than when she listens through the air. Why does the sound wave travel better through the solid wall than through air?

• When you put your ear on a solid surface, extra sounds are blocked out, allowing you to hear the sound better.

• Particles of a solid are closer together than particles of air, so they can transfer the compression of the sound wave more efficiently.

• When traveling through the air, the sound wave has a longer distance to travel, and some sound energy dissipates.

• Particles of a solid are easier to vibrate than particles of air.

Answer explanation

Particles of a solid are closer together than particles of air, allowing sound waves to transfer compressions more efficiently. This is why Charlotte hears the music better through the wall.

Which characteristics are properties of both transverse and longitudinal waves?

• Crest

• Trough

• Frequency

• Rarefaction

• Amplitude

Answer explanation

Frequency and amplitude are properties of both transverse and longitudinal waves. Frequency refers to the number of cycles per second, while amplitude measures the wave's height, affecting its energy.

Using the equation: wave speed = wavelength × frequency, determine the frequency of each wave shown in the diagram if the wave speed is 1.2 m/s and the wavelength for the high frequency wave is 0.3 m, while the wavelength for the low frequency wave is 0.8 m.

• High frequency wave: 4 Hz, Low frequency wave: 1.5 Hz

• High frequency wave: 2 Hz, Low frequency wave: 0.5 Hz

• High frequency wave: 3 Hz, Low frequency wave: 1 Hz

• High frequency wave: 1 Hz, Low frequency wave: 0.3 Hz

Answer explanation

To find frequency, use the formula: frequency = wave speed / wavelength. For the high frequency wave: 1.2 m/s / 0.3 m = 4 Hz. For the low frequency wave: 1.2 m/s / 0.8 m = 1.5 Hz. Thus, the correct answer is High frequency wave: 4 Hz, Low frequency wave: 1.5 Hz.

Calculate the frequency of the high-frequency wave. (Frequency = wave speed / wavelength. The wave speed is 0.5 m/s, and the wavelength of the high-frequency wave is 1 m / 15 waves.) What is the frequency of the high-frequency wave?

• 7.5 Hz

• 0.5 Hz

• 15 Hz

• 30 Hz

Answer explanation

To find the frequency, first calculate the wavelength: 1 m / 15 waves = 0.0667 m. Then, use the formula: frequency = wave speed / wavelength = 0.5 m/s / 0.0667 m = 7.5 Hz. Thus, the correct answer is 7.5 Hz.

Calculate the frequency of the low-frequency wave. (Frequency = wave speed / wavelength. The wave speed is 0.5 m/s, and the wavelength of the low-frequency wave is 1 m / 3 waves.) What is the frequency of the low-frequency wave? A) 1.5 Hz B) 0.5 Hz C) 3 Hz D) 0.33 Hz

• 1.5 Hz

• 0.5 Hz

• 3 Hz

• 0.33 Hz

Answer explanation

To find the frequency, use the formula: frequency = wave speed / wavelength. The wavelength is 1 m / 3 waves = 0.33 m. Thus, frequency = 0.5 m/s / 0.33 m = 1.5 Hz. Therefore, the correct answer is A) 1.5 Hz.