Answer:
I believe the answer is

Explanation:
I may be incorrect because I used to do this a long time ago but I believe I am correct
HOPE THIS HELPS!
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Answer:
Their speed in a vacuum is a constant value.
Explanation:
Electromagnetic waves consits of oscillations of electric field and magnetic field. The oscillations of these fields occur in a direction perpendicular to the direction of propagation of the waves, so they are transverse wave. Electromagnetic waves, contrary to mechanical waves, do not need a medium to propagate, so they can also travel through a vacuum. In a vacuum, their speed is constant and has always the same value, the speed of light:

The magnitude of charge on a proton and electron is the same, 1.602 x 10-19 C. Protons are +, and electrons -.