--%>

calculate the intensity I along y axis

As shown in the figure below, a source at S is sending out a spherical wave:

E1=(A×D/r) cos(wt-2πr/λ); where r is the distance to source S. In addition, there is another plane wave propagating along x axis: E2=Acos(wt-2πx/λ). 

These two waves both projected on a vertical screen as shown in the figure. Please calculate the intensity I along y axis (I should be a function of y, the distance from x axis). D is the distance between the screen and the source.

 

381_optics.png

Hint: For a wave E=E0cos (wt + q), I = 2 = E02. Also r = (D2 + y2)1/2.

For k<<1,  (1+k2)1/2» 1+k2/2.   cosA+cosB = 2cos[(A+B)/2] cos[(A-B)/2]

   Related Questions in Physics

  • Q : Explain Malus law Malus' law (E.L.

    Malus' law (E.L. Malus): The light intensity I of a ray with primary intensity I0 travelling via a polarizer at an angle theta among the polarization of the light ray and the polarization axis of the polarizer is specified by:

    Q : Explain Schroedingers cat

    Schroedinger's cat (E. Schroedinger; 1935): A thought experiment designed to exemplify the counterintuitive and strange ideas of reality that come all along with the quantum mechanics. A cat is sealed within a clos

  • Q : Define Siemens or SI unit of an

    Siemens: S (after E.W. von Siemens, 1816-1892): The derived SI unit of an electrical conductance equivalent to the conductance of an element which has a resistance of 1 O [ohm]; this has units of O-1.

  • Q : Explain Chronology protection conjecture

    Chronology protection conjecture (S.W. Hawking): The notion that the formation of any closed time like curve will (automatically) involuntarily be destroyed by the quantum fluctuations as soon as it is made. In another words, the quan

  • Q : Define Weber or SI unit of magnetic flux

    Weber: Wb (after W. Weber, 1804-1891): The derived SI unit of magnetic flux equivalent to the flux that, connecting a circuit of one turn, generates in it an electromotive force of 1 V as it is decreased to zero at a uniform rate in a period of 1 s; i

  • Q : Define Metre or SI unit of length Metre

    Metre: meter; m: The basic SI unit of length, stated as the length of the path traveled by light in vacuum throughout a period of 1/299 792 458 s.

  • Q : Explain Maxwells equations and its

    Explain Maxwells equations and its four elegant equation? Maxwell's equations (J.C. Maxwell; 1864): The four elegant equations that explain classical electroma

  • Q : Define Mediocrity principle Mediocrity

    Mediocrity principle: The principle that there is nothing predominantly interesting about our position in space or time, or regarding ourselves. This principle most likely first made its real manifestation in the scientific community whenever Shapley

  • Q : Polarization In a non-polar - molecule,

    In a non-polar - molecule, the centre of the nuclei and electron orbit overlap when such a molecule is positioned in electric field, the electrons are attracted with the positive charged of the anode and repelled by the negative charges of the cathode. Because of grea

  • Q : Problem on Orbit cycle Calculate the

    Calculate the hot and cold temperature after 25 orbits. Assume a 100kg spherical spacecraft made of aluminum. Assume that the spacecraft is in an equatorial orbit. How is calculation 1 different for a spacecraft in a 90 degree (polar) orbit?