<h2>
Answer:When electrons absorb or emit quantized units of energy in the form of photons.</h2>
Explanation:
When a electron is collided with a photon with exactly the same energy it would require to get to any of the farther orbits,electron transition takes place to an orbit depending on the energy of the photon.
When electrons emit exactly the same amount energy that is difference between the current energy level and the new level,then the electron makes a transition to the new level.
Formula for time: velocity/distance **Going to use GRESA
Given: v=65mi/hr d=115mi --- Required: time=? --- Equation: v/d --- Solution: 65mi/hr / 115mi = 0.57 hr --- Answer: 0.57 hr
D = 1/2 x g × t²
145 = 1/2 × 9.8 × t²
t = 5.4 s