Light and Optics Flashcards
An observer looking 42° up and away from rain may see a rainbow created from the wavelengths splitting apart as white light travels through the raindrops. What is the term for this phenomenon?
Dispersion - white light incident to face of prism comes out with split wavelengths, because wavelength related to index of refraction, where a small λ has a large n and a smaller angle of refraction when passing into a denser medium
The index of refraction (n) is equal to c/v and it is dependent on λ, because c = λf. What are some assumptions to be made from the aforementioned information?
Light of different wavelengths have different speeds and refract at different angles in different media.
Speed of Light
Measured in a vacuum, it is 3.00 X 10^8 m/s, where c=λf
Snell’s Law
Equation used to find either n or angle of refraction when passing from one medium to another: n1sinθ1=n2sinθ2
How does light reach the end of fiber optic cables without really showing up on the sides of the cables?
Total internal reflection occurs when the θ of light traveling from high n to low n is greater than the critical angle: n2/n1=sinθ1
Law of Reflection
θi = θr
Pointing a flashlight through a small slit leads to a spreading out effect called?
Diffraction, where there are bright and dark fringes. The dark fringes could be located with: a sinθ = nλ
How do polarizing sunglasses work?
The polarizing filters on the sunglasses only allow electromagnetic waves parallel to the filter through, leading to plane-polarized light and preventing glare from hitting the eyes.
Virtual Image
An image produced at a point where light does not actually converge.
Real Image
Image produced at a point where light actually converges.
Lens Makers’ Equation
1/f = 1/p + 1/q
Magnification
m = -i/o
A negative value means that the image is inverted.
What is the term for the distance between the focal point and the mirror or lens?
Focal Length
What type of mirror is your bathroom mirror and what type of image does it produce?
Assuming you have a normal bathroom mirror, it is a plane mirror where the incident light rays remain parallel after reflection. A plane mirror always produces a virtual image the same distance behind the mirror as the object is in front of the mirror.
Spherical Mirror
Curved mirror with a focal length equal to r/2.
What type of mirror is the make-up/ shaving mirror?
It is a converging mirror, which is concave, with a positive focal length. Beyond the focal point, an object in front of the converging mirror produces a virtual image. At the focal point, no image occurs. Before the focal point, an object produces a real image.
Diverging Mirror
A convex mirror that has a negative focal length and that always leads to virtual images.
Converging Lens
A thick-centered lens that converges light rays at a single point. An object beyond the focal point will produce a real, inverted image. Placed before the focal point, the object produces a real, upright image. The virtual side is on the same side as the object for lenses.
Diverging Lens
A thin-centered lens that always produces a virtual image.
Wavelengths (Å) of Spectrum
UV < 4000 Violet 4000 - 4250 Blue 4250 - 4900 Green 4900 - 5750 Yellow 5750 - 5850 Orange 5850 - 6500 Red 6500 - 7000 Infrared > 7000
What type of lenses does the eye have?
Lenses in contact, where the equivalent focal length follows this equation: 1/f = Σ1/f
What type of lens configuration are in telescopes and microscopes?
Lenses not in contact, where the magnification of the system involves multiplying the magnification of all of the individual lenses.
Monochromatic Light
Light of only one wavelength
Coherent Light
Light waves whose phase differences do not change with time
Interference
Amplitudes if light waves sum up
Electromagnetic Waves
A transverse wave with a magnetic field and electric field perpendicular to each other
Photon
It is an electric and magnetic wave perpendicular to each other and perpendicular to the direction of propagation.
Moving from a medium of low index of refraction to a medium with a higher index of refraction causes light to:
Slow down and bend towards the normal
Fermat’s Principle
Light takes the fastest path between two points.
Energy of Photon
E = hf
