Key Terms for the Production and Reflection of light

What is an LED and what does it stand for?

A light-emitting diode (LED) produces light as a result of an electric current flowing in semiconductors.

What is a light ray?

A light ray is a line on a diagram representing the direction and path that light is travelling.

What does luminous mean?

Luminous describes an object that produces its own light.

What is a mirror?

A mirror is any polished surface that reflects an image/light.

What does non-luminous mean?

Non-luminous refers to objects that do not produce their own light but can be seen by reflected light.

What is the normal (in optics)?

The normal is a line drawn perpendicular (90°) to the surface where the incident ray strikes.

What is a concave mirror?

A concave mirror is a converging mirror shaped like the inner surface of a sphere that reflects light inward.

What does it mean for light to converge?

To converge means light rays come together (meet) at a point after reflection or refraction.

What is a convex mirror?

A convex mirror is a diverging mirror shaped like the outer surface of a sphere that reflects light outward.

What is phosphorescence?

Phosphorescence is the process where a material absorbs ultraviolet light and then slowly emits visible light over time.

What is the principal axis?

The principal axis is the line through the center of curvature, the focus, and the vertex of a mirror.

What is radiation (in the context of light)?

Radiation refers to the emission of energy as electromagnetic waves or moving subatomic particles.

What is a real image?

A real image is an image formed when light rays actually meet at a point; it can be projected onto a screen.

What is a reflected ray?

A reflected ray is the ray that bounces off a reflective surface after hitting it.

What is reflection?

Reflection is the bouncing back of light from a surface.

What does translucent mean?

A translucent material transmits some incident light but scatters it, making objects behind it blurry.

What does transparent mean?

A transparent material transmits almost all incident light, allowing objects behind it to be seen clearly.

What is triboluminescence?

Triboluminescence is the production of light when certain crystals are scratched, crushed, or rubbed.

What is ultraviolet light?

Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than visible light but longer than X-rays.

What is the vertex (of a mirror)?

The vertex is the point where the principal axis meets the mirror’s surface.

What is a virtual image?

A virtual image is formed when light rays appear to meet behind a mirror; it cannot be projected on a screen.

What is visible light?

Visible light is the range of electromagnetic waves that the human eye can detect.

What is white light?

White light is composed of all the colors of the visible spectrum combined.

What is the angle of incidence?

The angle of incidence is the angle between the incident ray and the normal.

What is the angle of reflection?

The angle of reflection is the angle between the reflected ray and the normal.

What is bioluminescence?

Bioluminescence is the production of light by living organisms due to a chemical reaction with little or no heat produced.

What is the centre of curvature?

The centre of curvature is the center of the sphere of which the mirror is a part.

What is chemiluminescence?

Chemiluminescence is the production of light from a chemical reaction without an increase in temperature.

What is diffuse reflection?

Diffuse reflection occurs when light reflects off a rough surface and scatters in many directions.

What does it mean for light to diverge?

To diverge means light rays spread apart after reflection or refraction.

What is the electromagnetic spectrum?

The electromagnetic spectrum is the complete range of electromagnetic waves, from radio waves to gamma rays.

What is an electromagnetic wave?

An electromagnetic wave is a wave of energy made up of oscillating electric and magnetic fields that travels through space.

What is fluorescence?

Fluorescence is the immediate emission of visible light by a material that has absorbed ultraviolet light.

What is the focal point?

The focal point is the point where light rays parallel to the principal axis converge after reflection (for a concave mirror).

What is geometric optics?

Geometric optics is the study of light’s behavior using the concept of light rays to explain reflection and refraction.

What is incandescence?

Incandescence is the production of light as a result of high temperature.

What is incident light?

Incident light is light emitted from a source that strikes an object.

What is an incident ray?

An incident ray is the incoming ray that strikes a surface.

What is infrared light?

Infrared light is electromagnetic radiation with wavelengths longer than visible light but shorter than microwaves.

What’s a plane mirror

A plane mirror is a flat, smooth mirror that reflects light to form an image.

What are the 2 laws of reflection?

1.The angle of incidence equals the angle of reflection.

2.The incident ray, reflected ray, and the normal all lie in the same plane.

How does electric discharge cause light?

The electric energy excites electrons in the gas atoms. When these electrons fall back to lower energy levels, they release energy as visible light or other electromagnetic radiation.

What is the speed of light?

Light travels at about 3 × 10⁸ m/s in a vacuum.

Where does light fit in the electromagnetic spectrum?