Understanding Light: Properties, Reflection, and Mirrors

Light Source

A light source is an object that emits light. There are natural light sources and artificial light sources. Examples of natural light sources include the Sun and stars, while an example of an artificial light source is a light bulb.

Luminous Bodies

Luminous bodies possess the characteristic of emitting light themselves, such as the Sun or the flame of a candle.

Illuminated Bodies

Illuminated bodies do not produce light but receive it from another body and are able to reflect it. Examples include the Moon, a desk, or a wall.

Opaque Bodies

Opaque bodies do not allow light to pass through them. Examples include a wall or a table.

Translucent Bodies

Translucent bodies allow light to pass through partially, but the light is diffused so that objects cannot be distinguished clearly through them. An example is a frosted bathroom door.

Transparent Bodies

Transparent bodies allow light to pass through, making it possible to see objects behind them clearly. Examples include glass and water.

Propagation of Light

Light travels in straight lines.

Geometrical Optics

Geometrical optics studies optical phenomena and components using the concept of a straight line or ray of light and plane geometry. When these rays encounter bodies, they can be absorbed, reflected, or deflected. This perspective is useful in the process of optical instrument construction.

Speed of Light

Light travels at different speeds in different media. In a vacuum, light travels at approximately 299,774 km/s (approximately 300,000 km/s).

Absolute Refraction Index

The absolute refraction index (n) is the relationship between the speed of light in a vacuum (C) and the speed of light in a substance (Vs): n = C/Vs.

Reflection of Light

Reflection of light is the phenomenon where a beam of light strikes a highly polished surface and returns the rays to the medium from which it originated.

Elements of Reflection of Light

• Incident Ray: The ray that arrives at the surface.
• Reflected Ray: The ray that emerges from the point of incidence.
• The Normal: A line perpendicular to the plane at the point of incidence of the beam.
• Angle of Incidence: The angle formed between the incident ray and the normal.
• Angle of Reflection: The angle formed between the reflected ray and the normal.

Laws of Reflection of Light

• The incident ray, the normal, and the reflected ray lie on the same plane, which is perpendicular to the reflecting surface.
• The angle of incidence equals the angle of reflection.

Images

An image is a reproduction of an object by means of light rays.

Plane Mirror

A plane mirror is a highly polished surface that can reflect light with a reflective power of 95% or higher of the incident light intensity.

Spherical Mirror

A spherical mirror is a mirror shaped like a section of a sphere.

Elements of a Spherical Mirror

• C: Center of curvature
• R: Radius of curvature
• F: Focus of the mirror
• V: Vertex of the mirror
• f: Focal distance
• h: Optical axis

Principal Rays of a Concave and Convex Mirror

• Parallel Ray: A ray incident parallel to the optical axis is reflected through the focus.
• Central Ray: A ray directed towards the center of curvature is reflected back upon itself.