Try for free
DiscoverMobile appPricingFor schoolsHelpLogin
← Back to flashcardsQuick Flashcards

Year 9 Science - Waves, Light, and Inquiry

A comprehensive Year 9 lesson covering sound waves, light properties, optics, and scientific inquiry methods.

37 cards~13 min
Year 9 Science - Waves, Light, and Inquiry — Qwi
1 / 37

All flashcards in this set

1What type of wave are sound waves?
Answer

Longitudinal waves

Sound waves consist of compressions and rarefactions along the direction of propagation.
2Sound waves travel through {{solids}}, liquids and gases at different speeds.
Answer

solids

3Sound is reflected when it contacts a solid surface.
Answer

True

Reflection occurs when sound waves bounce off a solid or liquid surface.
4How do compressions differ from rarefactions in a longitudinal wave?
Answer

Compressions → high pressure | Rarefactions → low pressure

Compressions are regions where particles are close together; rarefactions are where they are spread apart.
5Does sound transfer energy, matter, or both?
Answer

Energy only

Sound waves convey energy through particle vibrations without moving matter.
6A labelled diagram of a longitudinal sound wave shows period, frequency, amplitude and {{wavelength}}.
Answer

wavelength

7Sound travels faster in gases than in liquids.
Answer

False

Sound travels faster in liquids than in gases because particles are closer together.
8Name one application of sound wave reflection.
Answer

Sonar

Sonar uses reflected sound waves to detect objects underwater.
9Compare sonar, ultrasound, and echolocation.
Answer

Sonar → ocean mapping | Ultrasound → medical imaging | Echolocation → animal navigation

All rely on reflected sound but differ in frequency and purpose.
10Which structure in the ear converts sound vibrations into neural signals?
Answer

Cochlea

The cochlea contains hair cells that translate mechanical vibrations into electrical impulses.
11The three ossicles are the hammer, anvil, and {{stirrup}}.
Answer

stirrup

12Conductive deafness is caused by damage to the auditory nerve.
Answer

False

Conductive deafness results from problems in the outer or middle ear, not the nerve.
13Difference between conductive and nerve deafness?
Answer

Conductive → outer/middle ear issue | Nerve → inner ear/auditory nerve damage

Conductive affects sound transmission; nerve affects signal processing.
14What dual nature does light possess?
Answer

Particle and wave

Light consists of photons (particles) and exhibits wave-like behavior such as interference.
15Light is an {{electromagnetic}} wave.
Answer

electromagnetic

16Light waves are transverse waves.
Answer

True

Light oscillates perpendicular to direction of propagation.
17How do reflection and refraction differ?
Answer

Reflection → bounce off surface | Refraction → bend entering new medium

Reflection changes direction without entering; refraction changes speed and direction when passing into another medium.
18What does the Law of Reflection state?
Answer

Angle of incidence equals angle of reflection

The incident and reflected rays make equal angles with the normal at the surface.
19Law of Reflection: {{angle of incidence}} = angle of reflection.
Answer

angle of incidence

20Plane mirrors always produce virtual images.
Answer

True

Plane mirrors form upright, virtual images located behind the mirror.
21Define refraction of light.
Answer

Bending of a wave as it passes from one medium to another

Change in speed causes the wave to change direction at the interface.
22The refractive index measures how much light slows down in a {{material}}.
Answer

material

23Refractive index is a property of a material.
Answer

True

It indicates how much light bends when entering the material.
24List three regions of the electromagnetic spectrum in order of increasing frequency.
Answer

Radio, microwave, infrared

Frequency increases from radio to microwave to infrared.
25An object's colour is determined by the light it {{absorbs}} or reflected by that object.
Answer

absorbs

26Colour of light is unrelated to its wavelength.
Answer

False

Colour corresponds to specific wavelengths; e.g., red ~ 700 nm.
27Which part of the eye focuses light onto the retina?
Answer

Lens

The lens refracts incoming light to converge on the retina.
28The {{retina}} converts light into neural signals.
Answer

retina

29Cataracts are listed as an eye defect.
Answer

True

Cataracts appear in the list of eye defects to correct.
30Difference between short sightedness and long sightedness?
Answer

Short sighted → focus in front of retina | Long sighted → focus behind retina

Both corrected with lenses of opposite power.
31What is the independent variable in an experiment?
Answer

What you change

It is the factor deliberately varied to test its effect.
32The dependent variable is the {{result}} measured in an experiment.
Answer

result

33Controlled variables are kept constant to ensure a fair test.
Answer

True

They prevent other factors from influencing the outcome.
34What are the two parts of an "If... then" hypothesis?
Answer

If → condition | Then → predicted outcome

The 'If' states the independent variable change; the 'Then' predicts the dependent variable response.
35When should you use a line graph instead of a column graph?
Answer

When data shows trends over continuous intervals

Line graphs are best for continuous variables like time.
36A graph must include a title, labelled axes, units, and even scales.
Answer

True

These elements ensure clarity and accurate interpretation.
37What is one way to improve accuracy in an experiment?
Answer

Reduce systematic errors

Identify and control sources of bias or measurement error.

Sound Waves

Sound travels as longitudinal waves. In these waves particles move back‑and‑forth in the same direction that the wave travels, creating regions of compressions (high pressure) and rarefactions (low pressure). This motion transfers energy only; matter itself does not travel with the wave.

Sound can move through all three states of matter, but its speed varies:

  • Fastest in solids – particles are close together, allowing rapid transmission.
  • Slower in liquids.
  • Slowest in gases.

When a sound wave meets a solid or liquid surface, part of the wave is reflected, producing echoes. An everyday example of this principle is sonar, which sends sound pulses underwater and listens for the reflected signal to locate objects.

Other practical uses of reflected sound include ultrasound in medical imaging and echolocation used by bats and dolphins to navigate.

Ear Anatomy and Hearing

The ear converts sound vibrations into neural signals through a series of specialised structures:

  • The three ossicles – hammer, anvil, and stirrup – transmit vibrations from the eardrum to the inner ear.
  • The cochlea contains hair cells that transform mechanical motion into electrical impulses sent to the brain.

Hearing loss can arise in two main ways:

  • Conductive deafness – caused by problems in the outer or middle ear that block sound transmission.
  • Sensorineural (nerve) deafness – results from damage to the inner ear or auditory nerve, affecting signal processing.

Light Waves

Light is an electromagnetic wave that exhibits a dual nature: it behaves both as a particle (photon) and as a wave. Light waves are transverse, meaning the oscillations occur perpendicular to the direction of travel.

Reflection and Refraction

Two fundamental behaviours of light are:

  • Reflection – the bounce of light off a surface. The Law of Reflection states that the angle of incidence equals the angle of reflection, measured from the normal to the surface.
  • Refraction – the bending of light as it passes from one medium to another, caused by a change in speed.

Plane mirrors always produce virtual images: upright, same size as the object, and appearing behind the mirror.

Refractive Index

The refractive index of a material quantifies how much light slows down inside it. A higher index means greater bending of the light ray when it enters the material.

Electromagnetic Spectrum

Within the spectrum, three regions ordered by increasing frequency are:

  1. Radio
  2. Microwave
  3. Infrared

Colour perception depends on the wavelength of light. Objects appear a certain colour because they absorb some wavelengths and reflect others; the reflected wavelengths reach our eyes.

Eye Structure

Light entering the eye is focused by the lens, which refracts the rays onto the retina. The retina converts light into neural signals that travel to the brain.

Common eye defects include:

  • Cataracts – clouding of the lens that impairs vision.
  • Short‑sightedness (myopia) – the image focuses in front of the retina.
  • Long‑sightedness (hyperopia) – the image focuses behind the retina.

Scientific Inquiry

Effective experiments rely on clear identification of variables:

  • Independent variable – the factor you deliberately change.
  • Dependent variable – the result you measure.
  • Controlled variables – aspects kept constant to ensure a fair test.

A hypothesis is framed as an "If… then…" statement, linking the independent variable (the "If" condition) to the predicted outcome (the "Then" result).

Data Presentation

Choosing the right graph type enhances interpretation:

  • Use a line graph when data shows trends over continuous intervals, such as time.
  • Use a column graph for discrete categories.

Every graph should contain a clear title, labelled axes with units, and evenly spaced scales to avoid misinterpretation.

Improving Accuracy

One key method to increase experimental accuracy is to reduce systematic errors. This involves identifying sources of bias or measurement error and controlling them throughout the investigation.