Powerpoint 1- From Modern Physics To Radiation Physics Flashcards
Event
A physical happening that occurs at a certain place at a certain time
Reference frame
Used to record the event. It consists of a coordinate system and a clock Eg (t,x,y,z)
Inertial reference frame
A frame in which newtons law of inertial is valid Non accelerating frames of reference Accelerating frames are NOT inertial frames
Two postulates
1) The laws of physics are the same in every inertial reference frame 2) the speed of light in a vacuum, measured in any inertial frame, always has the same value of c. It is independent of the source or observer
Space time
Space and time
Time dilation
The time difference between two events that occur at the same place in one frame is less that the time interval between the same events that is measured in another frame in which events occur at different places
Phenomena of special relativity
Time dilation Length contraction Relative velocity Mass-energy
Proper time
The time difference between events that happen at the same place in a reference frame
Length contraction
Objects length is larger when measured by an observer at rest with respect to it. If object is moving with respect to initial observer, that observer measures a smaller length
When to use relativistic energy
If the speed of the object is below 10% of speed of light or kinetic energy less than 0.5% of an object rest energy, non-relativistic expressions are accepted (error is small
γ
β
Relativistic mass
Relativistic momentum
Thermal radiation
Radiation emitted by hot objects In infrared region Intensity depends on wavelength
Blackbody
At a constant temperature, a perfect black body is an object that absorbed all the electromagnetic radiation that falls on it. Absorbs and re-emits radiation in continuous spectrum Temperature dependent
Relativistic Energy (E)
Mass Energy Equivalence
Relation between E and p
Relative Velocity
Doppler Effect
Transverse Doppler Effect
Photoelectric Effect
Compton Effect
