L02 Intro To Optics And Light Flashcards
Wave
A disturbance or oscillation that travels through space and matter, accompanied by a transfer of energy
4 types of wave
Mechanical, electromagnetic, transverse and longitudinal
Mechanical wave
Requires medium for propagation
Eg. water
Electromagnetic wave
Able to propagate through vacuum
Eg. light
Transverse wave
Components vibrate perpendicular to direction of propagation
Longitudinal wave
Components vibrate parallel to direction of propagation
Relationship btwn frequency and wavelength
↑ frequency : ↓ wavelength
↓ frequency : ↑ wavelength
Formula for wavelength/frequency
Velocity = frequency x wavelength(m)
Electromagnetic spectrum properties
- EM energy travels as transverse wave
- constant speed in vacuum at 3 x 10^8 m/s
- requires no medium to propagate
-Consists of varying electric and magnetic fields
•Vibrate perpendicular to each other and to direction of travel
•Vibrate at same frequency of the wave
- Unaffected by electric and magnetic fields
- Travel in straight line within limit set by diffraction
- Capable of being polarized
- Quantity of energy carried by the EM waves depends on magnitude of disturbance in the electric and magnetic fields
- Can be caused to produce interference effects
List the waves on the electromagnetic spectrum from longest to shortest wavelength (lowest to highest frequency )
- Radiofrequency Wave
- Microwaves
- Infrared
- Visible Spectrum
- Ultraviolet (UV) Radiation
- X-rays
- Gamma Rays
Terms describing light source
Source, point source, extended source, monochromatic source, polychromatic source
Source
Any object that emits electromagnetic radiation
Point source
A source either infinitely small or sufficiently far away
Extended source
A source with measurable area
Monochromatic source
A source that emits electromagnetic radiation of single wavelength or frequenc
Polychromatic source
A source that emits radiation of several wavelengths or frequencies
Wavefront
- Point source emit waves in all direction
* Arc / curve formed with centre at source by connecting same position e.g. trough / crest, on all waves
Law of Malus
Rays are perpendicular to wavefronts
Pencil rays
Group of rays emanating from a point source or single point on an extended source
Types of pencil rays
- Divergent pencil
- Convergent pencil
- Parallel pencil
Beam
Sum of all pencils emanating from a source or aimed towards an image
Pencil vergence
- Divergent pencils = -ve vergence
- Convergent pencils = +ve vergence
- Parallel pencils = zero vergence
Pinhole
One ray from object form one point on image
Pinhole formula
h/h’=a/a’
Depth of field
Distance object can move without affecting sharpness of image in specific fixed position
Depth of focus
Distance image screen can move while maintaining sharp image for fixed object position
