Electromagnetic Spectrum
Absorption
happens when a material takes in light and converts it into different forms of energy.
Constructive interference
happens when identical parts of two waves meet.
Destructive interference
happens when the opposite parts of two waves meet.
Light
interacts with matter, which can affect its behavior in different ways. travels in a straight path and tends to spread out from the source. In some sources such as lasers, the light spreads out less.
Wave model
light is an energy-carrying disturbance or vibration similar to sound and water ripples. Reflection is explained as the bouncing of light waves on a material it cannot pass through, similar to the echo of sound and ocean waves bouncing on a steep cliff. Refraction of light is the slowing down of the waves as light moves to a different medium. predicted that light is capable of interference, or waves amplifying or cancelling each other.
Particle model
light is made of a stream of particles traveling in a straight path. (According to Newton) since light travels in a straight line, it must be a particle because waves are known to bend through obstacles. Isaac Newton is among the leading proponents of particle model.
frequency (f)
number of complete waves passing through a point in a unit of time. inversely related to the period o f a wave.
Interference
overlapping of two or more waves into one wave whenever they pass through the same point.
Euclid of Alexandria
postulated that light "coming from the eye" travels in a straight line. also worked on the reflection of light.
Opaque Materials
those that selectively absorb colors. Most opaque materials around us convert light to heat but some materials convert some of the light to other forms of energy.
wave's period (T )
time it takes for the wave to finish one complete wavelength to pass through a point.
Speed (v)
distance divided by time.
wavelength (λ)
distance the wave covers per cycle of propagation.
What are the 2 types of Interference?
(1) Destructive Interference (2) Constructive Intererence
X-ray's Wavelength
1x10^-10 to 1x10^-8
Microwave's Wavelength
1x10^-3 to 1
Ultraviolet's Wavelength
1x10^-8 to 4x10^-7
Visible Light's Wavelength (Blue)
4.2x10^-7 to 4.7x10^-7
Visible Light's Wavelength (Green)
4.7x10^-7 to 5.3x10^-7
Visible Light's Wavelength (Violet)
4c10^-7 to 4.2x10^-7
Visible Light's Wavelength (Yellow)
5.3x10^-7 to 5.8x1^-7
Visible Light's Wavelength (Orange)
5.8x10^-7 to 6.2x10^-7
Visible Light's Wavelength (Red)
6.2x10^ to 7x7x10^-7
Infrared's Wavelength
7x10^-7 to 1x10^-3
Gamma Ray's Wavelength
Less than 1x10^-10
What is the order of the electromagnetic spectrum? (longest to shortest wavelength)
Radiowaves Microwave Infrared Visible Light (ROYGBV) Ultraviolet X-rays Gamma Rays
Refraction
bending of light as it travels from one medium to the other.
Reflection
bouncing back of light when it reaches the boundary between two media, and the light stays in the original medium.
James Clerk Maxwell
came up with the theory of electromagnetic wave, electric and magnetic fields that induce one another as they propagate. Hypothesized that light is an electromagnetic wave because the speed of electromagnetic wave matched the known speed of light.
White light
composed of different components of a spectrum: red, orange, yellow, green, blue, indigo, and violet. When an object reflects all the components of light, it appears white. However, when an object absorbs all the components of light, it appears black. An object that appears with a particular color means that the object absorbs most of the colors and reflects only the color of the object.
Thomas Young's double-slit experiment
demonstrated that light exhibits interference
Claudius Ptolemy
famous for his geocentric model of the universe, studied the refraction of light and color phenomena.
Radiowave's Wavelength
greater than 1 meter
Dispersion
separation of light into different colors may happen to a refracting light depending on the angle from which it entered a new medium and the nature of this medium.
Diffraction
spreading-out of light after passing through a narrow slit. When the opening is smaller, the diffraction is greater. The diffraction is also greater if the wavelength is longer.
Transmission
the passing of light through a material medium. The extent of the transmission of light depends on the type of the material. Transparent and translucent materials transmit light, but opaque materials do not. If light is not transmitted, it may have been reflected or absorbed.
Scattering
the splitting and bending of light into several random directions. (1) Transparent material, scattering is due to impurities present in the material. (2) Opaque material, light may scatter in different directions as it bounces off due to irregularities in the material's shape. Shorter wavelengths of visible light are scattered by nitrogen and oxygen molecules in the atmosphere, making the sky appear blue. During sunset, the light coming from the sun hits the atmosphere at a different angle making the sky appear red.
Electromagnetic Waves
transverse waves made of perpendicular electrical and magnetic field components. They do not need a medium to propagate, hence, they can travel through space. travel slower in denser materials or materials with molecules closer to one another.
James Bradley
used the apparent change in the position of stars as Earth revolves around the Sun to measure the speed of light. The value he obtained was 3.0 × 108 m/s. which is within 1% of the current estimate.
Heinrich Hertz
using Maxwell's theories, discovered radio waves by building devices that can produce and receive them. He determined that radio waves also travel at 3.0 × 108 m/s, and exhibit wave properties similar to that of light. This established that both radio waves and visible light are electromagnetic waves.
Christiaan Huygens
worked on a mathematical theory of the wave nature of light.