Which of the following is a true statement? A. Electromagnetic waves consist of only changing electric fields. B. Electromagnetic waves are longitudinal waves. C. Electromagnetic waves do not always need a medium to travel. D. Electromagnetic waves can vary in speed, wavelength and frequency.

CElectromagnetic waves don't always need a medium to travel. Note that they do vary in wavelength and frequency however their speed is fixed. Also, EM waves are always transverse and they consist of vibrating electric and magnetic fields.

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abidemiokin abidemiokin · Answer 2 · 2021-11-23T07:22:19-05:00

Electromagnetic waves do not always need a medium to travel is the right option. Option C is correct

Wave is a disturbance that travels through a medium and transfers energy from one point to another without causing any permanent displacement of its medium itself.

Waves can be mechanical or electromagnetic waves. Mechanical waves required a material medium for their propagation while electromagnetic does not require a material medium for their propagation

Hence from the given option, electromagnetic waves do not always need a medium to travel is the right option.

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