In the double-slit experiment of the figure, the electric fields of the waves ar
ID: 1500260 • Letter: I
Question
In the double-slit experiment of the figure, the electric fields of the waves arriving at point P are given by E1 = (2.97 ?V/m) sin[(2.10 × 1015)t] E2 = (2.97 ?V/m) sin[(2.10 × 1015)t + 39.2 rad], where time t is in seconds. (a) What is the amplitude of the resultant electric field at point P? (b) What is the ratio of the intensity IP at point P to the intensity Icen at the center of the interference pattern? In a phasor diagram of the electric fields, (c) at what rate would the phasors rotate around the origin and (d) what is the angle between the phasors?
Incident wave '2 Path length difference .Explanation / Answer
sina + sin(a+b) = 2cos(b/2)sin(a+b/2)
E1 + E2 = 2Eocos(phi/2)sin(2t+phi/2)
E = 2Eocos(phi/2)
Eo = 2.97 uV/m
phi 39.2 rad
E = 4.34 uV/m
part b )
I = 4Iocos^2(phi/2) = 2.14 Io
Icenter = $iocos^2(0) = 4Io
I/Icenter = 0.54
part c)
rate = w = 2.10 x 10^15 rad/s
part d )
angle = 39.2 rad = 2246 degree = 86 degree