For an electromagnetic wave propagating along the x-axis, the maximum value of the electric field is \( E_0=30\,\mathrm{V\,m^{-1}} \). What is the maximum value of the magnetic field?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( 10^{-7}\,\mathrm{T} \)
In an electromagnetic wave, the speed of light links the two field amplitudes as \( B_0=E_0/c \), with \( c=3\times10^{8}\,\mathrm{m\,s^{-1}} \).
\( \begin{aligned} B_0 &= \frac{E_0}{c} \\ &= \frac{30\,\mathrm{V\,m^{-1}}}{3\times10^{8}\,\mathrm{m\,s^{-1}}} \\ &= 10^{-7}\,\mathrm{T} \end{aligned} \)
NCERT (2026-27):
Nature of Electromagnetic Waves – “… It is also seen from Maxwell’s equations that the magnitude of the electric and the magnetic fields in an electromagnetic wave are related as
\( B_0=(E_0/c) \)\( \qquad (8.10) \)”