Waves and Electromagnetic Radiation Part 2

electric field

the area around a charged object that can exert a force on other charged objects

magnetic field

the area around a magnet that exerts a force on objects containing metals

electromagnetic wave

composed of electric and magnetic fields that radiates out from a source at the speed of light

speed of light (edgenuity)

3.00 × 10^8

When is an electromagnetic wave produced?

• charged particles are disturbed

• disturbed particles produce oscillating magnetic and electric fields

properties of an electromagnetic wave

• travels at the speed of light

• made of magnetic fields

• made of electric fields

• radiates from a source

electromagnetic spectrum

the range of wavelengths and frequencies of electromagnetic waves

electromagnetic spectrum (order left to right)

1. gamma waves

2. x-rays

3. ultraviolet

4. visible light

5. infrared

6. microwaves

7. radio

Planck’s constant

6.63 × 10^-38 J/s

formula for energy

E = hf

Energy = Planck’s constant x frequency

formula for speed of light in a vacuum

c = fλ
3.00 × 10^8 m/s = frequency (hz) x wavelength (m)

As a wave travels through different media,

speed changes but frequency remains the same

type of relationship between speed and wavelength

direct

x-rays usage

diagnosis, medical imaging

gamma rays usage

treatment of diseases, lasers

ultraviolet usage

destroy bacteria and viruses

detect counterfeit money

germicidal lamps

infrared usage

used in heat lamps, remote controls

microwaves usage

transmit information to cell phones

warm up food

radio waves usage

transmit information to radios

visible light usage

vision

polarization

visible light can be manipulated for eye protection through this process

• modify light waves so that they vibrate in a single plane

polarization process

Unpolarized light is filtered by a polarizer that has a vertical plane, allowing light with vertical oscillations to pass throug hand blocking light that oscillates in other directions. Then, another polarizer that has a horizontal plane is used to block the polarized light.

wave speed, frequency, wavelength formula

s = fλ

When light travels through media what does/does not change?

• light does not change frequency

• speed and wavelength change

Ancient Greek beliefs about light

• A wave is a disturbance that travels through spaces in the air

• A substance carrying particles that flow with velocity from a light

• A stream of rays that comes with velocity from the eyes of an observer

• The reuslt of rays taht leave teh eyes, reflect off an object, and interact with sunlight to become visible

reflection

particles bounce off a surface

refraction

• force pulls particles into medium

• opposite force pulls particles from medium

• light passes through one medium to another

theory that can be used to explain each phenomenon

diffraction & interference: wave theory

reflection & refraction: particle and wave theory

Isaac Newton

Thought of light as a stream of tiny particles discharged by luminous object that travel in straight paths

Christiaan Huygens

Thought that light is made of waves that can bend and spread out

Thomas Young

Performed the double slit experiment that supported the wave theory of light

• the wave spread through slits, in accordance with Huygens’ principle

• waves interfered, resulting in the diffraction pattern

James Clerk Maxwell

Explained how electric and magnetic fields can induce eachother

• concluded that light is produced by the interaction between electric and magnetic fields

Heinrich Hertz

Observed that radio waves have hte same properties as light

• concluded that light is made of waves

• discovered photoelectric effect in 1887

photoelectric effect

emissions of electrons from a metal when it is struck by light of certain frequencies

frequency threshold

minimum frequency to eject electrons

quantum

the smallest packet of electromagnetic energy that can be absorbed or emitted

photon

a quantum particle of electromagnetic energy with zero mass

• different kinds of light carry different amounts of energy

light’s dual nature

• travels and interacts with itself as though it is a wave

• interacts with matter as thoguh it is a stream of photons

uncertainty principle

the speed or location of a quantum particle cannot be measured simultaneously

• formulated by German physicist Werner Heisenberg in 1927

quantum mechanics

• deals with subatomic particles like electrons

• deals with matter such as photons

• led to a new and exciting field of quantum computing

superposition principle

states that a wave or particle can exist in the same position at the same time

quantum computing

takes the principles of superposition and the uncertainty principle to create a new way that information or data can be handled by computers

• traditional computers input data in 0 and 1

• with this 0 and 1 can exist in superposition, so 0 and 1 can exist at the same time

• allows a computer to calculate/process multiple data all at once

cybersecurity usage

• deals with the unauthorized use of information on a computer

• can encrypt info quickly and thwart hackers

formula for energy of photon

E = hf

energy of photon and frequency

direct relationship

incident ray

a light ray moving toward a boundary

reflected ray

a light ray bouncing off a boundary

do the incident/reflected ray have the same speed?

yes

Normal

denotes an imaginary line perpendicular to a boundary that goes through the point where an incident ray strikes the boundary

Angle of incidence (reflection)

the angle between teh incident ray and the normal

Angle of reflection

the angle between the reflect ray and the normal

law of reflection

states that 𝛳i and 𝛳r are equal

specular reflection

occurs when light strikes a smooth surface, resulting in light traveling in the same direction

diffuse reflection

occurs when light strikes a rough surface, resulting in the reflected light traveling in different directions

scattering

the deflection of light waves in all directions as they collide with particles or gas molecules in the atmospheres

• short wavelengths (blue/green) easily scattered by particles in the atmosphere

• short wavelenghts become more scattered as the amount of atmosphere they pass through increases

refraction diagram

also contains incident ray, refracted ray, normal, angle of incidence (𝛳1) and angle of refraction(𝛳2)

do the incident/refracted ray have the same speed?

no

optical density

measure of how much light a material allows to pass through

index of refraction (n)

measure of the bending of a refracted ray

ray bends away from normal

medium 1 is more dense

ray bends towards normal

medium 1 is less dense

index of refraction formula

n = speed of light in vacuum/speed of light in medium

Snell’s law

shows the relationship between the indices of refraction of the two media and the angles of incident and refraction

Snell’s law (formula)

n1sin𝛳1 = n2sin𝛳2

real image

formed by converging light rays that can be displayed on a screen

virtual image

formed by diverging light rays that cannot be displayed on a screen

center of curvature (C)

the center of the sphere from which a curved mirror was cut

principal axis

is the line that runs through the center of curvature to teh center of a mirror

vertex (V)

the point where the principal axis and mirror meet

radius of curvature (R)

the distance between teh center of curvature and the vertex

focal point (F)

the point on a mirror’s axis where reflected light converges or appears to diverge

focal length (f)

distance from center of the mirror to the focal point

object is in front of the center of curvature

in front of mirror

real

inverted

smaller

object is between F and V

behind mirror

virtual

upright

bigger

object is between C and F

behind mirror

real

inverted

bigger

object is on C

behind mirror

real

inverted

same size

convex mirrors

curved outwards

concave mirror

curved inwards

lens equation

1/f = 1/d0 + 1/di

magnification equation

M = hi/h0 = -di/d0

positive distance

behind the lens

negative distance

front of the lens

positive height

upright

negative height

inverted

magnficiation >1

bigger

magnification <1

smaller