All electromagnetic waves travel at the same speed in a vacuum: 3.0 x 10^5 (300,000) kilometres per second. some electromagnetic waves are part of the visible light spectrum and some do emit harmful radiation, but certainly not all. they travel fine on earth without the vacuum of space too.
This question is not complete, the complete question is;
An electron remains suspended between the surface of the Earth (assumed neutral) and a fixed positive point charge, at a distance of 5.3 m from the point charge. Determine the charge required for this to happen. The acceleration due to gravity is 9.8 m/s² and the Coulomb constant is 8.98755 x 10⁹ N.m²/C². Answer in units of C.
Answer: the charge required for this to happen is 1.7415 × 10¹⁹ C
Given the data in the question;
we know that gravitational force on electro = M×g
mass of electron m = 9.10938356 × 10⁻³¹ kilograms
charge of electron e = 1.60217662 × 10⁻¹⁹ coulombs
given that distance r = 5.3m and the Coulomb constant = 8.98755 x 10⁹ N.m²/C²
g = 9.8 m/s²
Now for the electron to be suspended, This will happen only if the electrostatic force is equal to weight of electron;