Question

In a radio wave if $E_0 = 10^{-4}$ V/m, then the magnitude of magnetic field and pointing vector is:

• A. $3.3 \times 10^{-13} W/m^2, 1.3 \times 10^{-11} W/m^2$
• B. $10^{-4} W/m^2, 1.3 \times 10^{-11} W/m^2$
• C. $3.3 \times 10^{-13} W/m^2, 1.3 \times 10^{11} W/m^2$
• D. $3.3 \times 10^{11} W/m^2, 1.3 \times 10^{-11} W/m^2$

Hint:

The Poynting vector represents the power flow in an electromagnetic wave.

Answer 1

The Correct Option is A

The magnitude of the magnetic field $B_0$ is related to $E_0$ as:
$$B_0 = \frac{E_0}{c}$$ And the Poynting vector magnitude is:
$$S = \frac{E_0^2}{\mu_0 c}$$ Substituting the given values, we find the correct values.