The so-called lyman-α photon is the lowest energy photon in the lyman series of hydrogen and results from an electron transitioning from the n = 2 to the n = 1 energy level. determine the energy in ev and the wavelength in nm of a lyman-α photon. (a) the energy in ev
(b)the wavelength in nm

a) 10.2 eV

b) 122 nm

Explanation:

a) First we must obtain the energy for each of the states, which is given by the following formula:

So, we have:

Now we find the energy that the electron loses when it falls from state 2 to state 1, this is the energy carried away by the emitted photon.

b) Using the Planck – Einstein relation, we can calculate the wavelength of the photon:

Where E is the photon energy, h the Planck constant and   the frequency.

Recall that , Rewriting for :

Recall that , So:

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.