You need to use your cell phone, which broadcasts an 833 MHz signal, but you're in an alley between two massive, radio-wave-absorbing buildings that have only a 16 m space between them. What is the angular width, in degrees, of the electromagnetic wave after it emerges?

Respuesta :

To solve this problem, the concepts related to single slit diffraction are necessary. The expression for the diffraction minimum in the single slit diffraction is

[tex]dsin\theta = m \lambda[/tex]

Where,

d= Slit width

m = Order of the diffraction

\lambda = Wavelength

The wavelength can be calculated through the expression

[tex]\lambda= \frac{c}{f}[/tex]

Where,

c = speed of light

f = Frequency

Note: The angular width of the electromagnetic wave that is width of the central maximum is equal to the twice of the angle of diffraction for the first minimum.

[tex]\theta'=2\theta[/tex]

Therefore, applying to our values we have,

[tex]\lambda= \frac{c}{f}[/tex]

[tex]\lambda = \frac{3.0*10^8}{833*10^6}[/tex]

[tex]\lambda =0.3601m[/tex]

To calculate the angle we can use the expression for diffraction and re-arrange for \theta, therefore

[tex]dsin\theta = m \lambda[/tex]

[tex]\theta = sin^{-1}(\frac{(1)0.3601}{16})[/tex]

[tex]\theta = 1.2896[/tex]

The angular widht would be

[tex]\theta'=2\theta[/tex]

[tex]\theta'=2(1.2896)[/tex]

[tex]\theta' = 2.58\°[/tex]

Therefore the angular width of the electromagnetic wave is [tex]2.58\°[/tex]