I need help with this

What produces light and all other electromagnetic waves? a) the photoelectric phenomena b) heated metals c) charged particles d) radioactive samples (pls explain if you can : )

What is the electric force acting between two charges of -0.0045 c and -0.0025 c that are 0.0060 m apart? use fe=kq1q2/r^2 and k = 9.00 x 10^9 n*m^2/c^2 a. 1.7 x 10^7 n b. -1.7 x 10^7 n c. -2.8 x 10^9 n d. 2.8 x 10^9 n

According to newton’s law of universal gravitation, which statements are true? as we move to higher altitudes, the force of gravity on us decreases. as we move to higher altitudes, the force of gravity on us increases. as we gain mass, the force of gravity on us decreases. as we gain mass, the force of gravity on us increases. as we move faster, the force of gravity on us increases.