A plane electromagnetic wave travels in free space along $$X$$-direction. If the value of $${\vec B}$$ (in $$tesla$$ ) at a particular point in space and time is $$1.2 \times {10^{ - 8}}\hat k.$$ The value of $${\vec E}$$ (in $$V{m^{ - 1}}$$ ) at that point is
A.
$$1.2\,\hat j$$
B.
$$3.6\,\hat k$$
C.
$$1.2\,\hat k$$
D.
$$3.6\,\hat j$$
Answer :
$$3.6\,\hat j$$
Solution :
Given : $$\vec B = 1.2 \times {10^{ - 8}}\hat kT$$
$$\vec E = ?$$
From formula,
$$E = Bc = \left( {1.2 \times {{10}^{ - 8}}T} \right)\left( {3 \times {{10}^8}m{s^{ - 1}}} \right) = 3.6\,V{m^{ - 1}}$$
$${\vec B}$$ is along $$Z$$-direction and the wave propagates along $$X$$-direction. Therefore $${\vec E}$$ should be along $$Y$$-direction.
Thus, $$\vec E = 3.6\,\hat j\,V{m^{ - 1}}$$
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