Year 8 Science: Light, Vision, and Medical Imaging

Vocabulary practice flashcards covering light properties, reflection, refraction, lenses, human eye anatomy, vision defects, and medical imaging techniques.

Luminous Objects

Objects that can produce light on their own, such as the Sun, stars, bulbs, tube lights, and candle flames.

Illuminated Objects

Objects that do not produce light on their own but reflect light falling upon them, such as the Moon.

Transparent Material

A material that allows light to pass through so objects on the other side can be clearly seen, such as the cornea.

Opaque Material

A material that lets no light pass through it, such as the human body.

Translucent Material

A material that lets light pass through, but objects on the other side cannot be seen clearly.

Incident Ray

The ray of light that falls on a surface.

Reflected Ray

The ray of light that gets reflected back from a surface.

Normal

An imaginary line drawn perpendicular ($90^\circ$) to the reflecting surface at the point of incidence.

First Law of Reflection

States that the angle of incidence ($\theta_i$) and the angle of reflection ($\theta_r$) are always equal to each other ($i = r$).

Second Law of Reflection

States that the incident ray, the reflected ray, and the normal all lie in the same plane.

Specular Reflection

Reflection that occurs when parallel rays of light fall on a smooth surface and reflect back as parallel rays in one direction, forming a clear image.

Diffuse Reflection

Reflection that occurs when parallel rays of light fall upon an irregular or rough surface and scatter in many directions.

Lateral Inversion

The phenomenon in mirror images where the left side of an object appears as the right side of the image and vice versa.

Endoscope

A medical instrument containing thin optical fibres that uses total internal reflection to carry light and images inside the body without large surgical cuts.

Total Internal Reflection

The reflection of light along the inner walls of an optical fibre that keeps light trapped inside so it travels efficiently around curves.

Periscope

An instrument containing two plane mirrors inclined at an angle of $45^\circ$ that uses multiple reflections to view hidden objects outside the line of sight.

Kaleidoscope

A cylindrical device containing three plane mirrors and small items like beads or broken glass that produces colorful, non-repeating patterns via multiple reflections.

Refraction

The bending of light as it moves from one material into another due to a change in its speed.

Dispersion of Light

The phenomenon of white light splitting into its seven constituent colors when passing through a transparent medium like a prism or water droplets.

Spectrum

The arrangement of the seven constituent colors of white light, abbreviated as VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red).

Electromagnetic Spectrum

The full range of light radiation ordered by energy, encompassing Radio Waves, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, and Gamma Rays.

Human Eye Anatomy

The spherical structure of the eye consisting of the cornea, conjunctiva, iris, pupil, lens, ciliary muscle, suspensory ligament, sclera, retina, fovea, vitreous chamber, and optic nerve.

Cornea

A 6-layered transparent covering on the outer side of the eye covered in tear fluid that protects the eye and refracts incoming light.

Iris

A dark-colored muscular ring in the center of the cornea containing pigments that controls the size of the pupil and regulates light intake.

Pupil

The small central opening in the iris through which light enters the eye.

Retina

The sensory cell layer located at the back of the eye where light is focused to create images and converted into electrical signals.

Rods

Sensory vision cells in the retina that activate in dim light or darkness and are responsible for light-dark vision.

Cones

Sensory vision cells in the retina that react to bright light and enable color perception.

Blind Spot

A point at the junction of the retina and the optic nerve that lacks sensory cells and does not support vision.

Vitreous Chamber

The inner space of the eyeball containing a gel-like substance that maintains eyeball stability and internal pressure.

Convex Lens

A converging lens that curves outward, bringing parallel rays of light together to a focal point.

Concave Lens

A diverging lens that curves inward, spreading parallel light rays apart.

Hyperopia

Long-sightedness caused by a weak refractive index where light focuses behind the retina, making nearby objects look blurry; corrected using a convex lens.

Myopia

Near-sightedness caused by a strong refractive index where light focuses in front of the retina, making distant objects look blurry; corrected using a concave lens.

Cataract

An eye condition where the lens becomes cloudy or foggy due to protein structures clubbing together, leading to vision loss.

Glaucoma

An eye defect caused by abnormal pressure inside the eyeball.

Presbyopia

An eye defect caused by the solidification of fluid in the eye lens.

Astigmatism

A vision defect caused by a non-uniform curvature of the cornea.

Types of Bone Fractures

Categorization of bone fractures seen in medical imaging, including transverse, linear, oblique nondisplaced, oblique displaced, spiral, greenstick, and comminuted.