In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of $3 × 10^{10} Hz$ and its amplitude is 30 V/m. The amplitude of the oscillating magnetic field is:

$1 × 10^{-7} T$

The correct answer is Option (1) → $1 × 10^{-7} T$

Electric field amplitude: $E_0 = 30 \, \text{V/m}$

In an electromagnetic wave: $B_0 = \frac{E_0}{c}$

Where $c = 3 \times 10^8 \, \text{m/s}$

$B_0 = \frac{30}{3 \times 10^8} = 1.0 \times 10^{-7} \, \text{T}$

Answer: Amplitude of magnetic field $B_0 = 1.0 \times 10^{-7}$ T