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Physics final

Terms in this set (78)

• Electromagnetic waves
Travel at the speed of light. Moving electrons or moving charged particles. Change in magnetic field produces a change in electric field which in turn produces a change in magnetic field and so on. Light is an electromagnetic wave and
• What are 9 Electromagnetic waves:
Gamma rays, X rays, Ultra-violet, infra-red,microwaves, TV, FM, AM Long waves.
• What is the shortest wavelength?
Ultra violet
• What is white:
presence of all colors
• What is black:
absence of color
• What is light:
packets of energy that consist of photons light is an electromagnetic wave.
• Speed of light
C = 2.99792458 X 10^8 m/s
• What is a bright spot:
the addition of waves
• What is a black spot:
subtraction of waves
• What is a fringe:
pattern of alternating bright and dark lines. Caused by defraction of waves
• Why do we get fringes:
light waves interfere with each other.
• Path difference
= one wavelength = ½ Y from one slit to the next is the path difference, the longer it is, the closer the focal point will be.
• Why is the sun red in the evening?
Because of moisture the angle of light waves are observed in a different way in the morning than at night because of the bending of light waves.
• Matter has properties of waves,
waves have properties of mater, wave and a particle
• Motion of charge is necessary to generate a magnetic field,
but an electric field is present regardless of whether the charge is moving.
• Xrays will pass through materials that are opaque to visible light. Radio waves
will also pass through walls that light can not penetrate.
• Polarized light?
Cancelation of one directional wave. One direction of field oscillation.
• Unpolorized light?
Mixture of many waves having different orientations for the electic field oscillations.
• Polymer?
Long chains of polarized light
• Defraction:
interference of light coming from different parts of the same slit or opening (fringes become less bright and fade out)
• Speed of light =
C = 2.99792458 X 10^8 m/s
• Path difference =
= distance between slits = ½ y
• Y=wavelength/w: w is the
width of the slit and x is the distance to the screen
• Second bright fringe
d,y/x = 2wavelength rearranged its y=2wavelengthx/d
• D,y/x = mwavelength: m is
an integer having possible values, 0,1,2,3ect.
• Adjacent slits: p = d, y/x, Y is the distance
from the center of the viewing screen and X is the distance from the grating to the viewing screen
• F =
= cycles/second and cycles/second = Hz
• Law of reflection:
The angle of incidence is equal to the angle of reflection and is taken from the normal.
• Law of refraction:
speed of light divided by velocity, it bends. Reflection: 0r=0i
• Refraction:
light rays pass into glass or water from air and is bent toward the axis by an amount that depends on index of refraction
Speed of light in a vacume
= 3 X 10^8 m/s
• Focal point:
half the radius, where all the light rays meet no matter, which angle it goes. Point where
• What is a focal point:
half the radius, where all the light rays meet no matter which angle it goes. It is the point where the rays cross. Point where rays focus.
• What is focal length:
distance from the center of the lens to the focal point. Depends on how strongly the surfaces are curved.
• Real image:
if image lies on the opposite side of the lens from object and also if light rays pass through the image point. Image is beyond focal point. If focal point is positive it's a real image if focal point is negative it's a virtual image for lenses. Distances for real objects or images are positive. Can be formed on a screen.
• Virtual image:
distances for virtual images are negative. Cant be formed on a screen. When an object lies inside the focal point of a positive lens. The light rays spread away from a point behind the object.
• Inverted image:
is when the image is upsidedown. Negative magnification = inverted
• Upright.:
positive magnification
• Magnification is
is the ratio of the image hight hi, to the object hight ho or M= Hi/Ho= -i/-o
• What determines an element: #
of protons
• Proton
nucleus of the hydrogen atom as well as a component of other nuclei. Has charge of e+ = 1.6 X 10^-19c.
• Electron:
-e
• Neutron:
has no charge and its mass is close to protons mass. Lower than atomic number
• Isotope
different- mass versions of the same element. Different isotopes have the same number of protons in the nucleus but different numbers of neutrons. Protons subtract electrons
• Atomic mass
number of protons + neutrons
• Atomic number:
When the number of electrons outside the nucleus must equal the number of protons inside the nucleus. Number of protons
• Electrostatic forces:
push protons out
• Strong nuclear force:
pulls everything together (protons together).
• Beta positive = position,
where radiation cant reach you, positive electron with positive charge, antielectron, is proton throws off positive charge becomes a neutron
• Atoms
number of protons and neutrons that determines whether its stable or not.
Alphas symbol, radiation material, charge, and penetrating ability.
∝ -2 protons, -2 neutrons, +, very little
Beta - symbol, radiation material, charge, and penetrating ability.
β, 1 electron, -, more than alpha.
Beta + symbol, radiation material, charge, and penetrating ability.
β,1 anti electron, + N/A, never get to you
Gamma symbol, radiation material, charge, and penetrating ability.
____, electromagnetic waves, no charge, very large
• Alpha:
2 neutrons and 2 protons are lost so that alpha can slim down.
• Beta-:
neutron turns into a proton.
• Beta+:
Proton turns into a neutron because to many protons not enough neutrons.
• Gamma:
nucleus is excited! Light energy
Half life: Τ 1/2
is time it takes for half the material to decay.
2T, 1/2 1/2
3T,1/2 1/2 1/2
4T,1/2 1/2 1/2 1/2
• Fusion:
Putting together, fusing together small atoms (energy source of the sun and stars) combines small nuclei to form somewhat larger nuclei Ex: (_1^3)H+ (_1^3)H ⟹(_2^4)He
• Fission:
splitting apart large atoms. Slitting apart of large nuclei into smaller fission products. Creates a chain reaction
• High temperatures and high densities required for a
fusion chain reaction is to explode a fission bomb to initiate the fusion reaction because the high temperature produced by the fission bomb creates the high kinetic energies necessary for fusion.
• Three places 3 million degrees:
Sun, atomic bomb, Princeton tokomak
• Frame of reference
where your standing and taking measurements
• Einstein said = as you go faster,
time slows down.Vbe = velocity of a moving object such as a boat, relative to the earth
Vbw= the velocity of an moving object relative to water
Vwe= the velocity of the water relative to the earth
V_bw+ V_We= V_be
• Einstein said = at the speed of light
time stops.
E=mc^2
electromagnetic waves can go at the speed of light.
People cant.
• Einstein said = as you go faster distance gets
smaller.*if its going fast enough a 100m train in length can go threw a 5m tunnel in length.
• Einstein said = as you go faster your mass
increases.
• Acceleration is equivalent to
to gravity a = g
• Because of acceleration light
bends
• Does gravity bend light?
Yes (Einstein)(matter warps space (gravity) objects follow the warpped space).
• Does gravity bend light?
No (newton)
• Matter warps space and also
time
• Escape velocity = is the 18000 amount you have to throw up to
stop and have it come back down.
• Black hole
Escape velocity exceeds speed of light( detect using speed and light).
• Acceleration determines wither a person that leaves and goes to space at the speed of light for what she thinks is a second, and comes back is older than a person that stays on earth while that person is traveling at the speed of light
-the person who left at the speed of light would be older.
• Proper time= time interval = is
is the elapsed time between two events measured in a frame of reference in which the two events occur at the same place within that form a of reference "stationary"
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