The velocity of electromagnetic wave is along the direction of
A.
$$B \times E$$
B.
$$E \times B$$
C.
$$E$$
D.
$$B$$
Answer :
$$E \times B$$
Solution :
An electromagnetic wave is the wave composed of the oscillations of electric and magnetic fields in mutually perpendicular planes and these oscillations are perpendicular to the direction of propagation of wave.
The direction of propagation of electromagnetic wave is given by poynting vector
$$S = E \times H = \frac{{E \times B}}{{{\mu _0}}}$$
This is parallel to $$E \times B.$$
Releted MCQ Question on Electrostatics and Magnetism >> Electromagnetic Waves
Releted Question 1
Out of the following options which one can be used to produce a propagating electromagnetic wave?
The electric field associated with an electromagnetic wave in vacuum is given by $$E = \hat i40\cos \left( {kz - 6 \times {{10}^8}t} \right),$$ where $$E,z$$ and $$t$$ are in $$volt/m,$$ metre and second respectively. The value of wave vector $$k$$ is