An oscillating current radiates an electromagnetic wave. How are its electric field and magnetic field oriented to each other and to the direction the wave travels?
AParallel to each other, and both parallel to travel
BParallel to each other, but perpendicular to travel
CPerpendicular to each other, but parallel to travel
DPerpendicular to each other, and both perpendicular to travel
Answer & Solution
Correct answer: D. Perpendicular to each other, and both perpendicular to travel
1. The electric field and the magnetic field of an electromagnetic wave are perpendicular to each other.
2. Both fields are also perpendicular to the direction in which the wave propagates.
3. So all three quantities, field, field and direction of travel, sit at right angles to one another.
4. An option that makes any pair of them parallel contradicts this three-way perpendicular arrangement.
_Source: OpenStax Physics (CC BY 4.0), Ch 15 "Light", section 15.1 The Electromagnetic Spectrum_
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