--%>

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 : Why the length of a standard meter

    Describe the reason in short why the length of a standard meter re-defined in the year of 1983?

  • Q : Define Landauers principle Landauer's

    Landauer's principle: The principle which defines that it doesn't explicitly take energy to calculate data, however instead it takes energy to remove any data, as erasure is a vital step in computation.

  • Q : Define Lux or SI unit of the illuminance

    Lux: lx: The derived SI unit of the illuminance equivalent to the illuminance generated by a luminous flux of 1 lm distributed consistently over a region of 1 m2; it therefore has units of lm/m2.

  • Q : Define Atwood's machine Atwood's

    Atwood's machine: The weight-and-pulley system devised to compute the acceleration due to gravity at Earth's surface by computing the total acceleration of a set of weights of identified mass about a frictionless pulley.

  • Q : What do you mean by the term nucleus

    What do you mean by the term nucleus? Describe in brief.

  • Q : Information in physics What do you mean

    What do you mean by the term information in physics?

  • Q : What is baryon decay Baryon decay - The

    Baryon decay -The idea expected by several grand-unified theories, those classes of subatomic particles termed as baryons (of which the nucleons -- neutrons and protons -- are members) are not eventually stable however indeed de

  • Q : Define Fermi paradox Fermi paradox (E.

    Fermi paradox (E. Fermi): E. Fermi's inference, simplified with the phrase, "Where are they?" questioning that when the Galaxy is filled with intelligent and scientific civilizations, why haven't they come to us hitherto? There are nu

  • Q : Define Photovoltaics Photovoltaics (PV)

    Photovoltaics (PV): It transform light directly into electricity. The typical current residential installation of 12m2 could produce around 1,300 kWh pa with a peak of around 1.9kW, though larger and more efficient installations are possibl

  • Q : Collision & Transition State Theory

    Assuming ideal gas: a)  Calculate the average velocity of a nitrogen molecule at 298K and compare to the velocity of a helium molecule at the same conditions. b)      Calculate the temperature wh