Waves MC Review

The distance traveled by a wave in one period is called?

• Frequency

• Period

• Speed of the Wave

• Wavelength

• Amplitude

Answer explanation

This is a definition identification question. asking you to identify the vocabulary word. The wavelength is the length of a complete cycle during the period.

Tags

NGSS.HS-PS4-1

Which of the following is the speed of a wave traveling with a wavelength λ, frequency f, and period T?

• v=λ/f

• v=f/λ

• v=λf

• v=fT

• v=f/T

Answer explanation

Because velocity has units of m/s, you can look at the options to determine that v=λf because λ has units of m and f has units of 1/s, creating units of m/s, what you are looking to determine.

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NGSS.HS-PS4-1

The frequency of a wave is doubled when the wavelength remains the same. What happens to the speed of the wave?

• It doubles

• It quadruples

• It remains unchanged

• It is cut to one half

• It is cut to one forth

Answer explanation

Looking at the v=λf equation, if λ stays constant, f and v are directly proportional and have the same exponents so twice f would be twice v.

Tags

NGSS.HS-PS4-1

The frequency of a wave increases when the speed remains the same. What happens to the distance between two consecutive crests?

• It increases

• It decreases

• It stays unchanged

• It increases first and then decreases

• It decreases first and then increases

Answer explanation

This is an example of v=λf. If v stays constant than λ and f are inversely related to each other. As one increases, the other decreases so as the frequency increases, the wavelength (the distance between crests) decreases.

Tags

NGSS.HS-PS4-1

Which of the following statements is true about transverse waves?

• They always have the same frequencies

• They always have the same velocities

• They always have the same wavelengths

• They always travel through a dense medium

• The particles vibrate in perpendicular direction with respect to the wave motion

Answer explanation

The question is asking which of the following statements will always apply to transverse waves. Note that the first 4 options say "always" meaning they must always be true. Frequencies, velocities, and wavelengths can change with respect to the equation v=λf so these are not always the same. Some transverse waves can move through the vacuum of space, which is not a dense medium. However, all transverse waves have displacements perpendicular to their direction of propagation.

Tags

NGSS.HS-PS4-1

Which of the following statements is true about longitudinal waves?

• They always have the same frequencies

• They always have the same velocities

• They always have the same wavelengths

• They always travel through a dense medium

• The particles vibrate along the same direction as the wave motion

Answer explanation

The question is asking which of the following statements will always apply to longitudinal waves. Note that the first 4 options say "always" meaning they must always be true. Frequencies, velocities, and wavelengths can change with respect to the equation v=λf so these are not always the same. Longitudinal waves can move through air, which is not a dense medium. However, all longitudinal waves have displacements parallel to their direction of propagation.

Tags

NGSS.HS-PS4-1

A wave travels on a string of length L, linear density μ (or m/L), and tension T. Which of the following is true?

• The wave speed is inversely proportional to the tension T

• The wave speed is directly proportional the linear density μ (or m/L)

• The wave speed increases with increasing tension T

• The wave speed increases with increasing linear density

• The wave speed only depends on the length of the string

Tags

NGSS.HS-PS4-1

A wave pulse travels a long a thin part of a horizontal cord and reaches another part of the cord which is

much thicker and heavier. Which of the following is true about the reflected and transmitted pulse by

the boundary in the cord?

• Reflected pulse Upright, Transmitted pulse Upright

• Reflected pulse Inverted, Transmitted pulse Inverted

• Reflected pulse Upright, Transmitted pulse Inverted

• Reflected pulse Inverted, Transmitted pulse Upright

• Reflected pulse zero amplitude, Transmitted pulse zero Amplitude

Answer explanation

When a wave travels from a less dense medium to a more dense medium, it is similar to a wave traveling and hitting a fixed boundary. The incoming wave will be inverted upon reflection.

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NGSS.HS-PS4-1

NGSS.HS-PS4-3

A wave pulse travels a long a thick part of a horizontal cord and reaches another part of the cord which

is much thinner and lighter. Which of the following is true about the reflected and transmitted pulse by

the boundary in the cord?

• Reflected pulse Upright, Transmitted pulse Upright

• Reflected pulse Inverted, Transmitted pulse Inverted

• Reflected pulse Upright, Transmitted pulse Inverted

• Reflected pulse Inverted, Transmitted pulse Upright

• Reflected pulse zero amplitude, Transmitted pulse zero Amplitude

Answer explanation

When a wave travels from a more dense medium to a less dense medium, it is similar to a wave traveling and hitting a flexible boundary. The incoming wave will stay in the same orientation upon reflection.

Two wave pulses with equal positive amplitudes travel on a cord approaching each other. What is the

result of the oscillations when the pulses reach the same point?

• It is constructive interference with twice the amplitude

• It is destructive interference with zero amplitude

• It is constructive interference with slightly greater amplitude

• It is constructive interference with the negative amplitude

• The standing wave is produced

Answer explanation

Since both waves are in the same orientations, when the waves superimpose, they will produce a wave with a larger amplitude which is constructive interference.

Tags

NGSS.HS-PS4-1