An electromagnetic wave has an electric field given by the expression (in Cartesian co-ordinates) : →E(x,t)=6.0cos(1.4×107x−3.43×1015t)^z. What is the direction of the magnetic field at time t = 0 and position x = 0 ?
A
-x
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B
+x
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C
-y
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D
+y
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Solution
The correct option is C -y ∵→E×→B||→V
where →V represents the direction of propogation.
Given that wave is propagating along + x-axis and →E along z-axis.
Hence →E×→B=+^i ⇒^k×→B=+^i⇒→B is along−^j