Question

The amplitude of the magnetic field in an electromagnetic wave is $3 \times 10^{-10}$ T. If frequency of the wave is $10^{12}$ Hz, then the amplitude of the associated electric field is:

• A. 9 V/m
• B. $9 \times 10^{-2}$ V/m
• C. $3 \times 10^{-10}$ V/m
• D. $3 \times 10^{-2}$ V/m

Hint:

In an electromagnetic wave, $E_0 = c \, B_0$ always holds true.

Answer 1

The Correct Option is A

Step 1: Relation between $E_0$ and $B_0$.
In an electromagnetic wave: \[ \frac{E_0}{B_0} = c \] where $c = 3 \times 10^8 \, \text{m/s}$.
Step 2: Substitute values.
\[ E_0 = c \cdot B_0 = (3 \times 10^8)(3 \times 10^{-10}) = 9 \, \text{V/m}. \]
Step 3: Conclusion.
The amplitude of the associated electric field is 9 V/m.