Nature of Light and Optics Flashcards

A complete set of vocabulary flashcards covering the concepts of light energy, reflection, refraction, lenses, eye structures, vision defects, and color mixing from the lecture notes.

Energy

The ability to do work or cause change, existing in forms such as mechanical, chemical, electrical, light, and thermal energy.

Light Energy

A form of radiant energy that travels in electromagnetic waves at a speed of $3 \times 10^8\,\text{meters per second}$ and can transfer energy through empty space without needing a medium.

Luminous Objects

Objects that produce their own light by converting other forms of energy into light energy, such as the Sun, stars, light bulbs, and flames.

Non-luminous Objects

Objects that do not produce their own light and are visible only when light falling on them is reflected, such as the Moon, planets, and mirrors.

Transparent Material

A material that allows all or most light to pass through it, such as clear glass or a window.

Translucent Material

A material that allows only some light to pass through it, such as frosted glass or sunglasses.

Opaque Material

A material that does not allow any light to pass through it, such as wood or a backpack.

Shadow

An area where light cannot reach because an opaque object blocks light traveling in straight lines.

Vacuum

Empty space with no particles or medium, through which light electromagnetic waves can travel.

Visible Light

The small portion of the electromagnetic spectrum detectable by human eyes, containing wavelengths from about $380\,\text{nm}$ to $740\,\text{nm}$.

Reflection

The process that occurs when a ray of light hits a surface and bounces off it.

Incident Ray

A ray of light that strikes a surface.

Reflected Ray

The ray of light that bounces off a surface after striking it.

Normal Line

An imaginary reference line drawn perpendicular ($90^\circ$) to a surface where a light ray strikes.

Law of Reflection

An optical law stating that when light hits a flat reflecting surface, the angle of incidence equals the angle of reflection ($i^\circ = r^\circ$).

Concave Mirror

A curved mirror that reflects light rays inward to a focal point, used in torches, solar heaters, and makeup mirrors.

Convex Mirror

A curved mirror that reflects light rays outward, always producing images that are upright and smaller than the object.

Refraction

The bending of light rays when passing from one medium into another of different optical density due to a change in speed.

Convex Lens

A lens that is thicker in the middle and curves outward, causing parallel light rays passing through it to refract inward toward a focal point.

Concave Lens

A lens that is thinner in the middle and curves inward, causing parallel light rays passing through it to refract outward.

Eye

A sense organ that detects light and converts light signals into electrical messages sent to the brain for sight.

Myopia (Short Sightedness)

A vision condition where close objects appear clear but distant objects are blurry because images form in front of the retina, corrected using a concave lens.

Hyperopia (Long Sightedness)

A vision condition where distant objects appear clear but close objects are blurry because images form behind the retina, corrected using a convex lens.

White Light

Light emitted by sources like the Sun or light bulbs that is made up of all the colours of the visible spectrum mixed together.

Dispersion

The separation of white light into its spectrum of colours (ROYGBIV) when passed through a glass prism, caused by different wavelengths refracting at different angles.

Primary Colours of Light

The base colours of light that cannot be created by mixing other light colours: Red, Green, and Blue.

Secondary Colours of Light

Colours of light created by combining two primary light colours: Magenta (Red + Blue), Cyan (Blue + Green), and Yellow (Green + Red).

Light Filter

A material that only allows light of its own colour to pass through while absorbing all other wavelengths.