Diffraction

Diffraction is the name given to one feature of wave behaviour. What does diffraction enable?

Feb/March 2016

A monochromatic plane wave, moving with speed $c$ and wavelength $\lambda$, is diffracted by a small aperture. The diagram shows successive wavefronts. How long will it take for some part of wavefront GH to reach point P?

Feb/March 2017

Which statement describes a condition that allows diffraction to take place?

Feb/March 2018

A water wave travels through a gap in two barriers. The wavefronts then spread out, as shown. What is this phenomenon called?

Feb/March 2020

A water wave undergoes diffraction as it goes through the gap between two barriers in a ripple tank. As it travels through the gap, the wave is seen to ‘spread out’. Which two factors both influence the amount of diffraction seen?

Feb/March 2021

Water waves with wavelength $\lambda$ are produced in a ripple tank. As they go through a narrow gap of width $d$ ($d$ is greater than $\lambda$), the waves are diffracted. Which combination of gap width and wavelength would produce the greatest reduction in the amount of diffraction?

Feb/March 2022

The diagram represents a water wave in a shallow tank. The wave passes through a gap in a barrier, causing diffraction and spreading out. The wavelength of the wave is much less than the width of the gap. The wavelength of the wave and the width of the gap are each altered by a small amount. Which combination of changes must make the spreading due to diffraction larger?

Feb/March 2025

Diagram 1 presents a ripple tank experiment where plane waves are diffracted by passing through a narrow slit in a metal sheet. Diagram 2 shows the same tank, but here the slit is wider. For both cases, the wave pattern arriving at the slit and the pattern leaving it are displayed. Which action would make the waves in diagram 1 diffract less, so that the emergent pattern becomes closer to the one shown in diagram 2?

May/June 2010

Diagram 1 shows a ripple tank experiment in which plane waves are diffracted as they pass through a narrow slit in a metal sheet. Diagram 2 shows the same tank with a slit that is wider. In both cases, the wave pattern arriving at the slit and the wave pattern after the slit are shown. Which action would make the waves in diagram 1 diffract less and therefore produce an emergent pattern closer to the one shown in diagram 2?

May/June 2010

Electromagnetic waves from an unidentified source in space were seen to be strongly diffracted as they passed through gaps of the order of $10^{-5}\,\text{m}$. Which type of wave are they most likely to be?

May/June 2010

Diagram 1 illustrates a ripple tank experiment in which plane waves pass through a narrow slit in a metal sheet and are diffracted. Diagram 2 shows the same tank with a slit that is wider. For each case, the wave pattern arriving at the slit and the resulting pattern after the slit are displayed. Which change would make the waves in diagram 1 diffract less, producing an emergent pattern more like the one shown in diagram 2?

May/June 2010

Under what circumstances does diffraction take place?

May/June 2011

A monochromatic plane wave moving with speed $c$ and wavelength $\lambda$ is diffracted by a small aperture. The diagram shows a succession of wavefronts. How long will it take for some part of the wavefront XY to reach point P?

May/June 2012

Which electromagnetic wave would produce the strongest diffraction effect for an atomic lattice with a spacing of about $10^{-10}\,\text{m}$?

May/June 2015

Continuous water waves pass through a gap in a barrier in a ripple tank and are diffracted. Which change would make the diffraction of the waves greater?

May/June 2016

Which statement gives an example of light diffraction?

May/June 2016

A hill lies between a television (TV) transmitter and a house, so the transmitter cannot be seen from the house. Even so, the house receives a good TV signal. Which wave effect at the hill allows the TV signal to reach the house?

May/June 2016

A water wave in a ripple tank undergoes diffraction when it travels through a gap in a barrier. Which two factors determine the angle of diffraction of the wave?

May/June 2018

The diagrams illustrate water-wave diffraction in a ripple tank as they move through a gap between two barriers. Which diagram is the correct one?

May/June 2019

During an experiment, water waves in a ripple tank are directed at a gap, as shown. Some diffraction of the water waves is seen. Which change to the experiment would give a clearer demonstration of diffraction?

May/June 2019

Which condition has to be satisfied for diffraction to happen when a wave travels through a gap?

May/June 2020

A hill lies between a television (TV) transmitter and a house. The transmitter is not visible from the house, but TV reception there is good. Which wave effect at the hill allows the TV signal to reach the house?

May/June 2020

Water waves in a ripple tank are arranged to travel through a narrow gap, as shown. Which diagram indicates the waves after they have gone through the gap?

May/June 2020

Which diagram most accurately illustrates how water waves diffract as they move through a gap in a barrier?

May/June 2021

Sound travels through air at $330\,\text{m s}^{-1}$. Which size of architectural features in a large concert hall would produce the best diffraction of sound waves with frequency $0.44\,\text{kHz}$?

May/June 2021

Water waves with wavelength $\lambda$ are travelling normally towards an obstacle that has a narrow opening. The opening has a width equal to $\lambda$. The waves leaving the opening spread out through an angle $\theta$, as illustrated. The opening is then gradually made wider. What, if anything, happens to $\theta$ and to the wavelength of the waves after they pass through?

May/June 2022

A bar oscillates at frequency $f$ to create water waves in a ripple tank. The waves then pass through an opening of width $x$ in a barrier, causing diffraction. Which pairing of vibration frequency and gap width will result in the smallest diffraction angle?

May/June 2022

The diagrams illustrate the diffraction of water waves in a ripple tank as they move through an opening between two barriers. Which diagram is the correct one?

May/June 2022

A ripple tank and a barrier containing one narrow opening are set up to show the diffraction of water surface ripples. At first, the wavelength of the ripples is five times smaller than the width of the gap in the barrier. Which change would make the diffraction more pronounced?

May/June 2023

A continuous progressive water wave in a ripple tank travels through an opening in a barrier and undergoes diffraction. The gap width is larger than the wavelength of the wave. Which alteration makes the wave spread out through a greater angle after it passes through the gap?

May/June 2023

An experiment is arranged to show the diffraction of water waves in a ripple tank. The waves travel through a gap of width $w$, and diffraction of the waves is seen. The wavelength of the waves is now doubled. What new gap width is required to produce the same degree of diffraction as before?

May/June 2023

A loudspeaker in a room is emitting music. The door into the room is open, and its width is $0.80\,\text{m}$. Sound waves of a range of frequencies travel through the opening and diffract. The speed of sound in air is $340\,\text{m s}^{-1}$. Which sound-wave frequency will diffract the most as it goes through the doorway?

May/June 2024

A water wave travels through an opening in a harbour wall and undergoes diffraction. The opening is $8\,\text{m}$ across. The wave moves directly towards the opening. For which wavelength is the diffraction of the wave the greatest?

May/June 2024

In a ripple tank, the water is at a fixed depth. A water wave with constant frequency moves towards a gap in a barrier in the ripple tank. The gap is reduced in width. Which diagram shows the wave before and after the barrier?

May/June 2025

A student produces a sound at point $R$ close to a building. A second student at point $S$, standing around the corner of the building, can hear the sound. The building is a solid structure and there are no other structures in the vicinity. Which effect best explains why the student at point $S$ is able to hear the student at point $R$?

May/June 2025

For an atomic lattice with spacing of about $10^{-10}\,\text{m}$, which electromagnetic wave would produce the strongest diffraction effect?

Oct/Nov 2010

Diffraction is seen when a wave goes past an obstruction. It is most pronounced when the wavelength and the obstruction are about the same size. For waves moving through air, what pairing of wave and obstruction would show diffraction most clearly?

Oct/Nov 2012

What does diffraction mean?

Oct/Nov 2013

Plane wavefronts in a ripple tank move through a gap, as illustrated. Which property of the wave is different at $Q$ from at $P$?

Oct/Nov 2014

Water waves with wavelength $\lambda$ undergo diffraction when they travel through a barrier opening of width $d$. Which pairing of wavelength and gap width would give the largest diffraction angle?

Oct/Nov 2015

The statements below describe the diffraction of waves as they travel through a narrow slit. Which statement is incorrect?

Oct/Nov 2015

Diagrams X and Y illustrate water waves moving around an obstacle and passing through a gap. The thick lines act as barriers to the waves, and each thin line shows a wavefront. Which statement is correct?

Oct/Nov 2016

Diagrams X and Y illustrate water waves travelling around an obstacle and passing through a gap. The thick lines act as barriers for the waves, and each thin line shows a wavefront. Which statement is correct?

Oct/Nov 2016

Diffraction may be seen when a wave goes past an obstacle. The diffraction effect is most pronounced when the wavelength and the obstacle are of comparable size. For waves moving through air, what pairing of wave and obstacle would show diffraction most clearly?

Oct/Nov 2017

A bar oscillates at frequency $f$ and generates water waves in a ripple tank. These waves then travel through a barrier that has a gap of width $x$, causing diffraction. Which pair of vibration frequency and gap width would give the least diffraction angle?

Oct/Nov 2017

Which diagram illustrates the diffraction of water waves in a ripple tank?

Oct/Nov 2017

A hill lies between a radio transmitter and a house, as illustrated. The transmitter is not visible from the house, yet radio waves from it are detected at the house. Why does this happen?

Oct/Nov 2017

A narrow slit is illuminated by a beam of laser light. Once it passes through the slit, the light strikes a screen. What pattern of light is observed on the screen?

Oct/Nov 2017

What is one example of wave diffraction?

Oct/Nov 2018

What occurs when waves pass through a gap whose width is equal to their wavelength?

Oct/Nov 2018

In what situation does diffraction take place?

Oct/Nov 2018

Water waves with wavelength $\lambda$ strike an obstacle at right angles and pass through a narrow opening. The opening has width equal to $\lambda$. The waves leaving the opening spread out through an angle $\theta$, as shown. The opening is then gradually made wider. Which changes, if any, happen to $\theta$ and to the wavelength of the waves that emerge?

Oct/Nov 2019

Which waves would provide the best demonstration of diffraction through a doorway?

Oct/Nov 2020

A transmitting mast emits microwaves with wavelength $1.5\,\text{cm}$ and radio waves with wavelength $1.5\,\text{km}$. A receiving aerial located behind a mountain can pick up the radio waves, but it cannot detect the microwaves. What is the reason for this?

Oct/Nov 2020

What does the term diffraction mean?

Oct/Nov 2020

A water wave in a ripple tank is diffracted as it travels through a gap in a barrier. Which two factors determine the angle of diffraction of the wave?

Oct/Nov 2021

A beam of laser light is aimed at a narrow slit. Once it passes out from the other side of the slit, the diffracted light then lands on a screen. What pattern of light is observed on the screen?

Oct/Nov 2021

Which diagram illustrates the diffraction of water waves in a ripple tank?

Oct/Nov 2021

A surface water wave travels through a gap between two barriers and is diffracted, as shown. What happens when the wave frequency is halved?

Oct/Nov 2022

Under what situation does diffraction take place?

Oct/Nov 2022

A sound wave with wavelength $0.50\,\text{m}$ travels through a doorway that is $1.0\,\text{m}$ wide between two rooms. Which change would make the diffraction greater?

Oct/Nov 2022

In an experiment, water waves in a ripple tank strike a gap, as shown. Some diffraction of the water waves is seen. Which change to the experiment would give a clearer demonstration of diffraction?

Oct/Nov 2023

A teacher is describing diffraction to a class of students. Which piece of apparatus is the most suitable for the teacher to use to show diffraction?

Oct/Nov 2023

Water waves in a ripple tank are sent through a narrow opening, as shown. Which diagram shows the waves after they have gone through the opening?

Oct/Nov 2023

An electromagnetic wave undergoes diffraction when it goes through a single slit. The slit width is greater than the wave’s wavelength. Which alteration will reduce the amount of diffraction of the wave?

Oct/Nov 2024

Surface water waves are generated in a ripple tank by a vibrating bar. The wavelength of the waves is $5.0\,\text{cm}$, and they move through a gap with width $20\,\text{cm}$. Which change would cause more diffraction to be observed?

Oct/Nov 2024