IGCSE Physics 0625 — Topic 3: Waves — Paper 2 (MCQ) Cambridge Challenge

Question 1

A seismologist detects two types of earthquake waves. P-waves arrive first and cause rock particles to vibrate back and forth along the direction the wave travels. S-waves arrive later and cause rock particles to vibrate at right angles to the direction of travel.

Which row correctly classifies these waves?

AP-wave: transverse S-wave: longitudinal BP-wave: longitudinal S-wave: longitudinal CP-wave: transverse S-wave: transverse DP-wave: longitudinal S-wave: transverse

Question 2

A radio station broadcasts at a frequency of 98.3 MHz. Radio waves travel at 3.0 × 10⁸ m/s. What is the wavelength of the broadcast?

A0.33 m B3.05 m C3.28 m D3050 m

Question 3

The diagram shows wavefronts approaching a gap in a barrier in a ripple tank.

The gap width is much larger than the wavelength. What is observed on the right side of the barrier?

ACircular wavefronts spread out in all directions BStraight wavefronts continue with slight bending only at the edges CNo wavefronts pass through the gap DWavefronts with a shorter wavelength emerge from the gap

Question 4

The diagram shows a wave on an oscilloscope screen. The time-base is set to 5 ms per division and the y-gain is 2 V per division.

What is the frequency of this wave?

A10 Hz B25 Hz C50 Hz D200 Hz

Question 5

In a ripple tank, water waves pass from a deep region into a shallow region at an angle. Which statement is correct?

AThe speed decreases and the waves bend towards the normal BThe wavelength increases and the waves bend away from the normal CThe frequency decreases and the waves bend towards the normal DThe speed increases and the waves bend away from the normal

Question 6

A student observes two waves in the laboratory. Wave P is produced by pushing a slinky spring back and forth along its length. Wave Q is produced by shaking a rope up and down.

Which row is correct?

AWave P has compressions and rarefactions; Wave Q has compressions and rarefactions BWave P has crests and troughs; Wave Q has compressions and rarefactions CWave P has compressions and rarefactions; Wave Q has crests and troughs DWave P has crests and troughs; Wave Q has crests and troughs

Question 7

A sound wave of frequency 440 Hz has a wavelength of 0.775 m in air. The same sound enters water, where its speed is 1480 m/s. What is the wavelength of this sound in water?

A0.775 m (unchanged) B0.297 m C1.91 m D3.36 m

Question 8

Noise barriers are built along a busy highway next to a residential area. The barriers reduce the noise reaching houses but do not eliminate it completely. Which statement best explains why some sound still reaches the houses?

ASound is refracted by the temperature gradient above the barrier BSound waves are transverse and can pass through the barrier material CSound reflects off the road surface and passes under the barrier DSound waves diffract over the top of the barrier

Question 9

A wave on a string has a speed of 12 m/s. A student doubles the frequency of the vibrations producing the wave, without changing the tension in the string. What happens to the speed and wavelength?

ASpeed stays at 12 m/s; wavelength halves BSpeed doubles to 24 m/s; wavelength stays the same CSpeed doubles to 24 m/s; wavelength doubles DSpeed stays at 12 m/s; wavelength doubles

Question 10

A ray of light hits a plane mirror. The angle between the incident ray and the mirror surface is 25°. What is the angle between the incident ray and the reflected ray?

A25° B50° C130° D65°

Question 11

A ray of light passes from air into a glass block. The angle of incidence is 50° and the angle of refraction is 30°. What is the refractive index of the glass?

A0.65 B1.00 C1.53 D1.67

Question 12

A glass block has a refractive index of 1.52. A ray of light travelling inside the glass hits the glass-air boundary. What is the critical angle for this glass?

A33.1° B41.1° C48.8° D56.9°

Question 13

A fibre-optic cable carries data for internet communication. The diagram shows a cross-section of the fibre.

Which statement correctly explains why light stays inside the core?

ALight reflects off the outer surface of the cladding BLight is continuously refracted by the cladding back into the core CThe cladding absorbs any light that escapes from the core DLight undergoes total internal reflection at the core-cladding boundary because the core has a higher refractive index than the cladding

Question 14

A pencil is placed in a glass of water and appears to be bent at the water surface when viewed from above. This happens because:

Alight rays from the underwater part of the pencil change speed and direction as they pass from water to air Bwater exerts a force on the pencil, bending it Clight rays from the pencil are reflected at the water surface Dtotal internal reflection occurs at the water surface

Question 15

The refractive index of diamond is 2.42. The critical angle of diamond is approximately:

A24.4° B41.3° C67.6° DIt cannot undergo total internal reflection

Question 16

The diagram shows a converging lens with focal length f = 10 cm. An object is placed at a distance of 15 cm from the lens.

Which describes the image formed?

AReal, inverted, and the same size as the object BVirtual, upright, and magnified CReal, inverted, and magnified DReal, inverted, and diminished

Question 17

Light travels from air into a glass prism. The refractive index of the glass is 1.50. The angle of incidence at the first surface is 45°. What is the angle of refraction inside the glass at this surface?

A22.5° B30.0° C33.3° D28.1°

Question 18

A doctor uses an endoscope to examine a patient's stomach. The endoscope contains bundles of optical fibres. Which condition must be met for light to undergo total internal reflection inside the fibres?

ALight must travel from a less dense to a more dense medium at any angle BLight must travel from a more dense to a less dense medium at an angle greater than the critical angle CLight must travel from a more dense to a less dense medium at an angle less than the critical angle DLight must travel from a less dense to a more dense medium at an angle greater than the critical angle

Question 19

White light passes through a glass prism and a spectrum is produced on a white screen. The diagram shows the arrangement.

In the diagram, ray P is at the top and ray Q is at the bottom of the spectrum. Which statement is correct?

AP is violet and Q is red; violet is refracted the least BP is red and Q is violet; red is refracted the least CP is red and Q is violet; violet is refracted the least DP is violet and Q is red; red is refracted the least

Question 20

A diverging (concave) lens is used to correct a student's vision. An object is placed 20 cm from the diverging lens. Which statement about the image is always true?

AThe image is real, inverted, and magnified BThe image could be real or virtual depending on distance CThe image is virtual, inverted, and diminished DThe image is virtual, upright, and diminished

Question 21

A ray of light inside a glass block (n = 1.50) hits the glass-air boundary at an angle of incidence of 35°. The critical angle for this glass is 41.8°. What happens to the ray?

ATotal internal reflection occurs and all light is reflected back BThe ray passes into air and bends towards the normal CThe ray passes into air and bends away from the normal DThe ray continues in a straight line without bending

Question 22

In laser eye surgery (LASIK), a laser is used to reshape the cornea. The laser produces monochromatic light. What does "monochromatic" mean?

AThe light has a single high intensity BThe light contains all wavelengths of the visible spectrum CThe light has a single wavelength (or frequency) DThe light travels in a straight line without spreading

Question 23

A converging lens has a focal length of 8 cm. An object is placed 6 cm from the lens. What type of image is formed, and on which side of the lens?

AReal image on the opposite side of the lens from the object BVirtual image on the same side of the lens as the object CNo image is formed DReal image on the same side of the lens as the object

Question 24

A multi-step calculation: A ray of light travels from water (n = 1.33) into air. Calculate the critical angle for the water-air boundary, and determine what happens when the angle of incidence is 50°.

ACritical angle is 48.8°; light undergoes total internal reflection BCritical angle is 48.8°; light refracts into the air CCritical angle is 41.2°; light undergoes total internal reflection DCritical angle is 41.2°; light refracts into the air

Question 25

Which list shows electromagnetic waves in order of increasing wavelength?

AGamma rays, X-rays, ultraviolet, visible, infrared, microwaves, radio waves BRadio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays CGamma rays, ultraviolet, X-rays, visible, infrared, radio waves, microwaves DRadio waves, infrared, microwaves, visible, X-rays, ultraviolet, gamma rays

Question 26

A satellite TV system uses a geostationary satellite. Which statements about geostationary satellites and the signals they use are correct?

1. The satellite orbits the Earth once every 24 hours
2. The satellite remains above the same point on the Earth's surface
3. The signals are carried by radio waves
4. The signals are carried by microwaves

A1, 2, and 3 only B1, 3, and 4 only CAll four statements are correct D1, 2, and 4 only

Question 27

Which electromagnetic radiation is used to sterilise surgical instruments in hospitals, and why is it effective?

AInfrared, because it heats and kills bacteria BUltraviolet, because it causes mutations in bacterial DNA CGamma rays, because they destroy the DNA of microorganisms DMicrowaves, because they vibrate water molecules in bacteria

Question 28

An analogue signal and a digital signal both travel along a cable. Both pick up noise during transmission. Which statement is correct?

AThe digital signal can be regenerated perfectly but the analogue signal cannot BBoth signals can be perfectly cleaned up by amplification CThe analogue signal can be regenerated perfectly but the digital signal cannot DNeither signal can be cleaned up after noise is added

Question 29

Which statement about X-rays is NOT correct?

AX-rays can pass through soft tissue but are absorbed by bone BX-rays travel at the speed of light in a vacuum CExcessive exposure to X-rays can cause cancer DX-rays have a longer wavelength than visible light

Question 30

A property shared by all electromagnetic waves is that they:

Atravel at the same speed in a vacuum Bcan ionise atoms Chave the same wavelength Drequire a medium to travel

Question 31

A hospital uses different types of electromagnetic radiation. Which row correctly matches the radiation to its medical use?

AInfrared for taking X-ray images; gamma rays for killing cancer cells BUltraviolet for taking X-ray images; infrared for thermal imaging CX-rays for imaging bones; gamma rays for treating cancer tumours DGamma rays for imaging bones; X-rays for treating cancer tumours

Question 32

Which statement correctly describes a danger of microwave radiation to the human body?

AMicrowaves cause sunburn on exposed skin BMicrowaves can cause internal heating of body tissue CMicrowaves cause mutations in DNA leading to cancer DMicrowaves ionise atoms in body cells

Question 33

A submarine emits a sonar pulse towards the ocean floor. The pulse takes 0.64 s to return. The speed of sound in seawater is 1520 m/s. What is the depth of the ocean floor below the submarine?

A486.4 m B972.8 m C108.8 m D2375 m

Question 34

An ambulance approaches a student standing on a London street with its siren on. As it passes and moves away, the pitch of the siren appears to change. Which statement is correct?

AThe pitch increases as the ambulance approaches because the siren gets louder BThe pitch appears higher as the ambulance approaches and lower as it moves away, due to the compression and stretching of wavefronts CThe actual frequency produced by the siren changes as the ambulance moves DThe speed of sound increases when the ambulance approaches, making the pitch higher

Question 35

The diagram shows air particles at one instant as a sound wave passes through them from left to right.

What are the regions labelled X and Y?

AX is a crest and Y is a trough BX is a rarefaction and Y is a compression CX is high pressure and Y is high density DX is a compression and Y is a rarefaction

Question 36

A student stands 85 m from a large building and claps her hands. She hears the echo 0.50 s later. What is the speed of sound calculated from this experiment?

A170 m/s B340 m/s C42.5 m/s D680 m/s

Question 37

An ultrasound scan is used to create an image of an unborn baby. The ultrasound frequency used is 3.5 MHz. Which statement about this process is correct?

AUltrasound uses high-frequency sound waves; reflections from tissue boundaries create the image BUltrasound uses electromagnetic waves that can safely penetrate the body CUltrasound is preferred over X-rays because X-rays cannot penetrate tissue DThe 3.5 MHz frequency is within the range of human hearing

Question 38

In a concert hall, an engineer needs to design the hall so the audience can hear clearly from all seats. Which design feature would help reduce unwanted echoes?

AUse smooth, hard walls to reflect sound towards the audience BInstall curved reflective panels to focus sound at the centre CUse soft, textured materials on walls to absorb reflected sound DMake the hall as large as possible to increase the time before echoes return

Question 39

A fishing boat uses sonar to locate a shoal of fish. The sonar pulse travels at 1500 m/s in seawater and is reflected from the fish 0.12 s after it is sent. At the same time, the boat's depth finder shows the ocean floor is 200 m below. Where are the fish relative to the ocean floor?

A90 m above the ocean floor B110 m above the ocean floor C20 m above the ocean floor DOn the ocean floor

Question 40

You can hear someone talking around a corner of a building but you cannot see them. Which statement best explains this?

ASound waves travel faster than light waves, so they reach you first BSound waves reflect off the ground but light waves do not CSound waves have a much longer wavelength than light waves, so they diffract significantly around the corner DLight waves are absorbed by the building but sound waves pass through it

Paper 2 — Multiple Choice

Section A: General Properties of Waves (3.1)

Section B: Light (3.2)

Section C: Electromagnetic Spectrum (3.3)

Section D: Sound (3.4)