Year 9 General Science: Energy, Light and Sound Revision

This set of vocabulary flashcards reviews key terminology for year 9 science, specifically focusing on wave properties, electromagnetic radiation, mirrors, and optics.

Transverse Wave

A wave in which the particles of the medium move perpendicularly to the direction of energy transfer.

Longitudinal Wave

A wave in which the particles of the medium vibrate parallel to the direction of energy transfer.

Compression

The region in a longitudinal wave where the particles are closest together.

Rarefaction

The region in a longitudinal wave where the particles are furthest apart.

Wavelength

The distance between two consecutive corresponding points on a wave, such as from crest to crest.

Amplitude

The maximum displacement of a particle from its rest position; determines the loudness of sound or brightness of light.

Frequency

The number of waves that pass a fixed point per second, measured in Hertz ($Hz$).

Pitch

The human perception of how high or low a sound is, determined by the frequency of the sound wave.

X-rays

Electromagnetic radiation used in medical imaging to view internal bone structures and in airport security scanners.

Microwaves

Electromagnetic radiation used for heating food and for satellite and mobile phone communications.

Gamma Radiation

High-energy electromagnetic radiation used to kill cancer cells (radiotherapy) and sterilize medical equipment.

Ultraviolet

Radiation present in sunlight that can cause tanning or sunburn; used in water purification and for detecting forged banknotes.

Visible light

The only part of the electromagnetic spectrum that can be detected by the human eye.

Infrared

Radiation felt as heat; used in remote controls, thermal imaging cameras, and night vision equipment.

$$Shortest\,Wavelength$$

In the electromagnetic spectrum, Gamma Radiation has this property.

$$Longest\,Wavelength$$

Among the list of radiations (X-rays, Microwaves, Gamma, UV, Visible, Infrared), Microwaves have the longest wavelength.

Myopia

Nearsightedness; a condition where near objects are seen clearly but distant objects appear blurred.

Hyperopia

Farsightedness; a condition where distant objects are seen clearly but close objects appear blurred.

Concave Mirror

A mirror that curves inward like the inner surface of a sphere, causing light rays to converge (meet).

Convex Mirror

A mirror that curves outward like the outer surface of a sphere, causing light rays to diverge (spread out).

Reflection

The process where light or sound waves bounce off a surface.

Refraction

The bending of light as it passes from one medium to another of different density, resulting in a change of speed.

Transparent

A type of material that allows almost all light to pass through, so objects can be seen clearly (e.g., clear glass).

Translucent

A type of material that allows light to pass through but scatters it, so objects on the other side appear blurry (e.g., frosted glass).

Opaque

A type of material that does not allow any light to pass through; it either reflects or absorbs all incident light.

Law of Reflection

A physical law stating that the angle of incidence ($i$) is equal to the angle of reflection ($r$).