n Flashcards
What is the wave equation (in terms of E field)?
What is the Phase vector equal to?
What are the solutions to the wave equation?
(a) for Plane waves, (b) for Spherical waves
Can waves of light be observed directly?
NO! With detectors, we always observe INTENSITY rather than the waves directly.
To observe wave phenomena, all photons need to be _____ ?
All photons must be coherent(approximately the same).
State the Poynting Vector. What does the Poynting vector describe?
The Poynting vector describes the ENERGY FLOW of an EM wave.
What is the Intensity of an EM wave (eq) ?
Derivation of intensity equation
Time average, given by equation on image.
More info on steps on other side
- E_ x B_ = IE_I IB_I sin(a)
- Average of sin(theta) is 0 (sin wave oscillates between -1 and +1).
- IEI_ IB_I = EB (now not vector)
- cos^2 oscillates between 0 and +1, with an average of 1/2 (so replace cos^2 with 1/2 when pulling out avg brackets)
What is the most relevent property between two waves for superposition?
Relative Phase/Phase difference is the most important property between 2 waves.
What is the equation for constructive interference of a Spherical wave/for double slit?
What is the equation for destructive interference of a spherical wave/for double slit?
State the phase difference for both of the cases above in terms of path length difference.
State the general equation for the position on a screen (double slit). State equation for the postion of mininum and maximum on a screen.
L is the distance between the slit and screen.
To observe wave properties of light, waves must be coherent. State the two types of coherence.
Temporal Coherence, Spatial coherence.
What does Temporal and Spatial coherence mean?
Temporal coherence: All photons contributing to interference pattern must be of the same wavelength.
Spatial coherence: All photons must have same momentum/propagate in same direction.
