Properties of Waves Practice Questions

State what is transferred by the ripples as they travel across the pond.

As the ripples reach the leaf, the leaf does not move towards the edge of the pond.

Explain how the motion of the leaf provides evidence that the water itself does not travel across the pond.

Use Figure 1 to determine the wavelength of the wave.

wavelength = .............................................................. cm

Use Figure 1 to determine the amplitude of the wave.

amplitude = .............................................................. cm

State what is meant by the frequency of a wave.

Which of these is a longitudinal wave?

Put a cross ( ☒ ) in the box next to your answer.

☐ A light from a lamp

☐ B sound in air

☐ C ripples on the surface of water

☐ D a wave on a stretched guitar string

Describe the difference between a transverse wave and a longitudinal wave.

Ripples on the surface of a tank of water have a frequency of $8.0\ \mathrm{Hz}$ and a wavelength of $0.025\ \mathrm{m}$.

Calculate the speed of the ripples.

speed = .............................................................. m/s

During a thunderstorm, the sound of thunder travels $1700\ \mathrm{m}$ through the air in $5.0\ \mathrm{s}$.

Calculate the speed of sound in air.

speed = .............................................................. m/s

Describe how the vibrating cone causes a sound wave to travel through the air to the student.

Explain how the sound wave travels from the loudspeaker to the student without any air travelling from the loudspeaker to the student.

Calculate the speed of sound obtained from these results.

speed of sound = .............................................................. m/s

The three times recorded by student B are very different from each other.

Explain one reason for this variation.

Describe one change the students could make to their method to obtain a more accurate value for the speed of sound, and explain the effect of this change.

On Figure 2, draw a line from point P to show the direction in which the ripples travel in the shallow water.

State and explain what happens to the wavelength of the ripples when they enter the shallow water.

State what is meant by a wavefront.

Describe how the student can measure the frequency of the ripples.

The student counts $36$ ripples passing a fixed point in $15\ \mathrm{s}$. The wavelength of the ripples is $2.5\ \mathrm{cm}$.

Calculate the speed of the ripples.

speed = .............................................................. m/s

State the relationship between the wavelength of the ripples and their frequency shown by these results.

Use the results to show that the speed of the ripples is the same at every frequency.

Give your values of speed in m/s.

Calculate the wavelength of this sound in air.

wavelength = .............................................................. m

Calculate the period of this sound wave.

Give your answer in standard form.

Use the equation
$$\text{period} = \frac{1}{\text{frequency}}$$

period = .............................................................. s

A student is asked to find the speed of ripples on the surface of water.

The student is given this equipment:

• a ripple tank with a motor-driven straight bar to make ripples
• a signal generator to control the motor
• a lamp and a screen
• a stroboscope
• a metre rule
• a stopwatch

Figure 1 shows the apparatus.

Figure 1

Describe how the student can use this equipment to obtain an accurate value for the speed of the ripples.

Your answer should include how the wavelength and the frequency are measured, and should comment on how suitable the equipment is.

Explain what happens to the direction and to the wavelength of the sound wave as it crosses the boundary into the water.

The frequency of the sound is $250\ \mathrm{Hz}$.

Calculate the wavelength of the sound in the water.

wavelength = .............................................................. m

A diver swims down into the lake. Sunlight entering the water contains all the wavelengths of visible light, but at a depth of $20\ \mathrm{m}$ very little red light remains.

Explain this observation.

Calculate the speed of sound obtained from these measurements.

Give your answer to 3 significant figures.

speed of sound = .............................................................. m/s

Explain why timing $20$ clap intervals gives a more accurate value for the speed of sound than timing a single clap interval.