Rectilinear Propagation of Light

It is a dark image formed by intercepting light rays

Shadow

“In a homogenous and isotropic medium, light travels in a straight line”

Isaac Newton

It is blocked by an opaque object will produce a shadow known as Umbra (absolute geometric shadow)

Point source

It is blocked by an opaque object will produce a shadow with 2 regions

Extended source

A Latin word which means “shade” of the shadow with sharp boarder, the inner part of the shadow which is completely dark

Umbra

It is derived from the Latin word “paene” which means “nearly”, it is the outer region of partial darkness around the umbra

Penumbra

An annular eclipse where the region that begins past the end of the umbra cone.

Antumbra

The uniform central region of illumination

Full Illumination

The outer annular region of illumination with partial darkness

Partial Illumination

Shadow formed will be the same shape as the aperture

True

A natural phenomenon that further demonstrates the Law of Rectilinear Propagation of Light

Eclipse

The earth moves between the sun and the moon, blocking sun’s light

Lunar Eclipse

It happens when the moon is between the earth and the sun; the moon’s shadow covers part of the earth

Solar Eclipse

Type of solar eclipse when the moon passes between the sun and earth but the alignment is not perfect and leaving a crescent shaped Sun

Partial Solar Eclipse

Type of solar eclipse when the moon located in the middle of the sun, and it doesn’t completely cover the entire disk of the sun. This results in a thin ring of sunlight that is visible around the outside of the moon

Annular Solar Eclipse

Type of solar eclipse when the moon completely blocks the sun, creating a shadow on the earth’s surface. This results a visible halo around the dark moon in front of the sun

Total Solar Eclipse

It is the simplest type of camera which doesn’t use a lens to form the image of an object; it consists of a light-tight box of adjustable length and dark interior, also known as Camera Obscura

Pinhole Camera

Arab physicist who first described the camera obscura effect

Alhazen

He is the first to be able to manipulate the image by fitting the pinhole camera with convex lenses and mirrors, i.e. concave mirror would enable the device to reflect an image right side up

Giovanni Battista della Porta

It is used to solve problems involving rectilinear propagation of light, they pair of triangles which share a common apex/angle; wherein their side lengths are congruent

Similar Triangles

The path of a single photon or particle of light

Light Ray

Light rays are spread apart as if originating from a point

Divergent Pencil

Light rays come together to meet at a single point

Convergent Pencil

Light rays never meet

Parallel Pencil

Collections of different pencils of light arising from an extended source

Beam of Light

The reciprocal of the distance from the point in question to the source or focus. General term by which convergence or divergence of light may be expressed

Vergence

Type of Lunar Eclipse when entire moon passes through full shadow

Total Lunar Eclipse

Type of Lunar Eclipse where some part of the moon passes through full shadow

Partial Lunar Eclipse

Type of Lunar Eclipse when moon passes only through partial shadow

Penumbral Lunar Eclipse