Light: Reflection, Spherical Mirrors, and Sign Conventions

Comprehensive vocabulary flashcards covering the nature of light, reflection laws, spherical mirrors, ray diagrams, image characteristics, and Cartesian sign conventions.

Natural Sources of Light

Light sources that exist naturally without human intervention, such as sunlight, fireflies, and fire.

Artificial Sources of Light

Man-made sources created to produce light, such as electric bulbs, torches, and candles.

Luminous Object

An object that can produce its own light, such as a torch, a bulb, or the Sun.

Non-Luminous Object

An object that cannot produce its own light and is visible only by reflecting light, such as a book or a pen.

Rectilinear Propagation of Light

The characteristic property of light to travel in a straight line.

Divergent Beam

A beam of light in which the rays spread outwards from a single point source.

Convergent Beam

A beam of light in which the rays travel towards each other and meet at a single common point.

Parallel Beam

A beam of light composed of rays that travel parallel to one another without converging or diverging.

Diffraction

The bending of light when it passes by a tiny, negligible obstacle or aperture.

Reflection of Light

The phenomenon of the bouncing back of light rays into the same medium when they strike a surface.

Regular Reflection

Reflection that occurs when light strikes a plain, smooth, shiny surface (such as still water, glass, or polished metal), causing the reflected rays to bounce back parallel to one another.

Irregular Reflection (Diffused Reflection)

Reflection that occurs when light strikes a rough, non-shiny surface (such as a wall or sand), causing the reflected rays to scatter in various non-parallel directions.

Incident Ray

The ray of light falling onto or striking a reflecting surface from a light source.

Point of Incidence

The specific point on a surface where an incident ray strikes.

Reflected Ray

The ray of light that bounces back from the surface at the point of incidence.

First Law of Reflection

The law stating that the incident ray, the reflected ray, and the normal at the point of incidence all lie in the same plane.

Second Law of Reflection

The law stating that the angle of incidence is always equal to the angle of reflection ($\angle i = \angle r$).

Lateral Inversion

The reversal of an object's left and right sides in the image formed by a plane mirror.

Concave Mirror

A spherical mirror with a polished outer surface and an inner reflecting surface curved inwards; also known as a converging mirror.

Convex Mirror

A spherical mirror with a polished inner surface and an outer reflecting surface curved outwards; also known as a diverging mirror.

Spherical Mirror Rule 1

A ray of light traveling parallel to the principal axis passes through the principal focus ($F$) after reflection.

Spherical Mirror Rule 2

A ray of light passing through the centre of curvature ($C$) retraces its own path back after reflection.

Spherical Mirror Rule 3

A ray of light passing through the principal focus ($F$) reflects and travels parallel to the principal axis.

Spherical Mirror Rule 4

A ray of light incident at the pole ($P$) or any specific point on a spherical mirror reflects symmetrically in accordance with the laws of reflection.

Concave Mirror: Object between $C$ and $F$

Produces an image located beyond the centre of curvature ($C$) that is real, inverted, and magnified.

Concave Mirror: Object at Infinity

Produces an image located at the principal focus ($F$) that is real, inverted, and highly diminished (point-sized).

Concave Mirror: Object at $C$

Produces an image located at the centre of curvature ($C$) that is real, inverted, and the exact same size as the object.

Concave Mirror: Object beyond $C$

Produces an image located between the principal focus ($F$) and the centre of curvature ($C$) that is real, inverted, and diminished.

Concave Mirror: Object at Focus ($F$)

Produces an image formed at infinity that is real, inverted, and highly magnified.

Concave Mirror: Object between $F$ and $P$

Produces an image behind the mirror that is virtual, erect, and highly magnified.

Real Image

An image formed when light rays actually meet at a point after reflection or refraction; it is always inverted and can be obtained on a screen.

Virtual Image

An image formed when light rays do not actually intersect but appear to diverge from a point; it is always erect and cannot be captured on a screen.

Convex Mirror: Object at Infinity

Produces an image behind the mirror at the focus ($F$) that is virtual, erect, and highly diminished (point-sized).

Convex Mirror: Object between Infinity and Pole

Produces an image behind the mirror between the pole ($P$) and focus ($F$) that is virtual, erect, and diminished.

Cartesian Sign Convention: Origin and Principal Axis

The convention where the pole ($P$) of the spherical mirror is taken as the origin and the principal axis is aligned along the coordinate $x$-axis ($X'X$).

Cartesian Sign Convention: Object Placement

The convention stating that the object must always be positioned on the left side of the mirror.

Cartesian Sign Convention: Reference Point for Distances

The rule establishing that all distances along the principal axis must be measured starting from the pole ($P$) of the mirror.