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Electromagnetic Waves — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsElectromagnetic Waves1 Mark
MCQ
An electromagnetic wave radiates outwards from a dipole antenna, with E0​ as the amplitude of its electric field vector. The electric field B0​ which transports significant energy from the source falls off as:
  • A
    $\frac{1}{\text{r}^3}$
  • B
    $\frac{1}{\text{r}^2}$
  • C
    $\frac{1}{\text{r}}$
  • D
    Remains constant.
✓

Answer

  1. $\frac{1}{\text{r}}$

Explanation:

An antenna that produces the Electromagnetic wave are radiated outwards. The amplitude of electric field vector (E0​). This electric field vector transports the energy from the source through the medium.

The electric field intensity of the wave from the source at a distance is inversely proportional to the distance between the source and the point.

$\text{E}_0=\frac{1}{\text{r}}$

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