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In an electromagnetic wave, how is energy conveyed?

1. Energy is carried in the direction of the magnetic field
2. Energy is carried in the direction of the electric field
3. Energy is shared equally along the electric and magnetic fields
4. Energy is carried in a direction perpendicular to both fields

Correct answer: Energy is carried in a direction perpendicular to both fields

Solution

The Poynting vector S = (1/mu0) (E x B) points perpendicular to both E and B and gives the direction of energy flow (the direction of propagation).

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