Answer: 1.99 W/m 2.
- A 3.98 W/m<sup>2</sup>
- B 1.99 W/m<sup>2</sup>
- C 7.96 W/m<sup>2</sup>
- D 0.99 W/m<sup>2</sup>
Correct answer: B. 1.99 W/m<sup>2</sup>
Explanation: I = P/(4πr<sup>2</sup>) = 100/(4π × 2<sup>2</sup>) = 100/(50.27) ≈ 1.99 W/m<sup>2</sup>.
In an electromagnetic wave, the oscillating electric field (E) and magnetic field (B) are perpendicular to each other and to the direction the wave travels - a purely transverse wave that needs no medium, unlike sound.
Concept context
Maxwell's equations, EM spectrum, properties, and applications of each band.