IGCSE Physics Waves & sound topical questions

Label the wave quantities.

1. (a)Name the distance from one crest to the next crest.[1]
2. (b)Name the maximum displacement from the undisturbed position.[1]
3. (c)Name the quantity measured in hertz.[1]
4. (d)Write the equation linking wave speed, frequency and wavelength.[1]

A drum skin vibrates 200 times each second, producing sound in air.

1. (a)State the frequency of the sound.[1]
2. (b)State whether humans can hear this sound, with a reason.[1]
3. (c)The sound travels at 340 m/s in air. Calculate its wavelength.[2]

Copy and complete using the words longitudinal or transverse.

1. (a)A wave on a rope is ______.[1]
2. (b)A sound wave is ______.[1]
3. (c)State which of these two waves has vibrations parallel to its direction of travel.[1]
4. (d)Give one more example of a transverse wave.[1]

In a ripple tank, water waves have a wavelength of 0.80 m and a frequency of 2.5 Hz.

1. (a)Calculate the speed of the waves.[2]
2. (b)State how many wavefronts pass a fixed point each second.[1]
3. (c)The waves meet the edge of a barrier and curve around behind it. Name this effect.[1]

A ripple tank produces waves with a frequency of 6.0 Hz. A stroboscope frozen at 6.0 flashes per second shows the wavefronts stationary, spaced 4.0 cm apart.

1. (a)State why the wavefronts appear stationary under the strobe.[1]
2. (b)Calculate the speed of the water waves in m/s.[3]
3. (c)The waves meet deeper water and speed up to 0.30 m/s. Calculate the new wavelength.[1]

A student claps in time with the echoes from a large flat wall 66 m away. 20 clap-echo cycles take 7.7 s.

1. (a)Explain why each clap-echo cycle corresponds to the sound travelling twice the wall’s distance.[1]
2. (b)Calculate the total distance travelled by the sound in 20 cycles.[2]
3. (c)Calculate the speed of sound from these results.[2]
4. (d)State one way to improve the accuracy of this method.[1]

A ship’s sonar emits ultrasound pulses downwards and receives echoes from the seabed. The pulses have frequency 60 kHz.

1. (a)Explain why the pulse is described as ultrasound.[1]
2. (b)An echo returns 0.50 s after transmission. Taking the speed of sound in sea water as 1500 m/s, calculate the depth of the water.[3]
3. (c)State one other use of ultrasound.[1]

Ripples of frequency 4.0 Hz travel at 0.30 m/s in the deep part of a tank. They enter the shallow part, where their speed falls to 0.20 m/s.

1. (a)Calculate the wavelength in the deep water.[2]
2. (b)Calculate the wavelength in the shallow water.[1]
3. (c)State the wave property that stays the same across the boundary, and explain why.[2]

An oscilloscope connected to a microphone displays a sound wave. The screen shows 4 complete cycles, and the timebase is set to 10 ms across the whole screen. The sound travels in air at 340 m/s.

1. (a)Calculate the frequency of the sound.[2]
2. (b)Calculate the wavelength of the sound in air.[2]
3. (c)A second trace shows 8 complete cycles across the same screen. State and explain how its pitch compares.[1]

A harbour wall has a wide entrance cut into it, 30 m across. Sea waves of wavelength 5.0 m arrive parallel to the wall, and later waves of wavelength 25 m arrive.

1. (a)Describe the shape of the wavefronts just beyond the entrance for the 5.0 m waves.[2]
2. (b)Describe and explain how the spreading of the 25 m waves compares.[3]
3. (c)Name the effect responsible for the spreading.[1]

An ultrasonic scanner is used on a patient. A pulse of frequency 3.0 MHz enters the body, reflects off the boundary between two soft tissues and returns after 8.0 × 10⁻⁵ s. Ultrasound travels at 1400 m/s in this tissue.

1. (a)Calculate the wavelength of the 3.0 MHz ultrasound in the tissue.[2]
2. (b)Calculate the depth of the reflecting boundary.[3]
3. (c)The scanner next detects a second boundary at twice the depth. State the return time of its echo, and explain why ultrasound rather than audible sound is used for scanning.[2]

A steel rail is checked for hidden cracks using ultrasound, which travels at 5900 m/s in steel. A probe on the top surface sends pulses straight down. A crack runs horizontally 0.30 m below the surface, and the bottom of the rail is 0.60 m below the surface.

1. (a)Explain why ultrasound rather than audible sound is used for this test.[1]
2. (b)Calculate the time between sending a pulse and receiving the echo from the crack.[3]
3. (c)Show that an echo from the bottom of the rail would arrive later, with a calculation.[2]