Question

According to the electromagnetic wave theory, light consists of electric and magnetic fields which are--.
A. Parallel to each other
B. Perpendicular to each other
C. Inclined at an angle of ${{45}^{o}}$ to each other
D. None of these.

Answer 1

Hint: We know that electromagnetic waves are periodic changes in electric and magnetic fields, which propagate through space. Propagation of the electromagnetic field is in the direction of$\overrightarrow{E}\times \overrightarrow{B}$. The nature of EM waves is transverse and hence electric and magnetic, both fields are perpendicular to the propagation of electromagnetic waves.

Complete step by step answer:

It has been known that the electromagnetic waves are produced by accelerated electric charges. An accelerated charge produces a magnetic field in the surroundings region which gives rise to an electric field.
If $\overrightarrow{E}$ is along the y-axis and $\overrightarrow{B}$ is along the z-axis, the direction of the propagation is along $\overrightarrow{E}\times \overrightarrow{B}$ i.e. along the x-axis as shown in the figure, the fields are shown as function of x coordinate at given time t.
Consider a single electromagnetic wave propagating perpendicular to both electric and magnetic fields in magnified form. Hence the magnetic field and electric field are perpendicular to each other.

So, the correct answer is “Option B”.

Note: Both the E and B fields attain their maximum (and minimum) value at the same time and at the same point in space i.e., they oscillate in the same phase with the same frequency. EM waves follow or obey the principle of superposition of waves. It does not require a medium to propagate.