Quantisation of Energy-Physics short questions answers

1.What is the ground state energy of the electron in the hydrogen atom hydrogen?
ans:
The electron in a Hydrogen atom can only have certain energies. These energies are called the Hydrogen's “energy levels”. The different energy levels of Hydrogen are denoted by the quantum number n where n varies from 1 for the ground state (the lowest energy level) to ∞, corresponding to unbound electrons. In practice, electrons with high n (e.g. 100 or more) are so weakly bound that even weak disturbances will pull the electron away.

E = -	E0
	n2

where E0 = 13.6 eV (1 eV = 1.602×10-19 Joules) and n = 1,2,3… and so on so that the ground state has energy E1= -13.6 eV

so, the ground state energy of the hydrogen atom is -13.6eV.

2.What would happen if the electrons in an atom were stationary?

ans:

If an electron in Hydrogen atom becomes stationary, that is it's velocity is 0 then there will be a well defined momentum which will also be 0.

By the uncertainty principle if the uncertainty in momentum is 0 ( i.e. That it is well defined) then the uncertainty in position is INFINITE.

Therefore the atom will not exist. 

This literally means that the atom in electron is stationery then the electron would fall into the nucleus.

3.Distinguish between the excitation potential and ionization potential?

ans:

This is the energy required in ev to excite a ground state atom to its excited state. When electrons jumps from ground state level (n=1) to another energy level (n=2) the corresponding energy is called 1st excitation potential energy and corresponding potential is called 1st excitation potential.
1st excitation energy =3.4ev-(13.6ev)=10.2ev

1st excitation potential=10.2v
ionization potential energy is defined as the minimum energy required in ev to excite a neutral atom to its ionized state i.e it is the minimum energy required in ev to excite an electron from n=1 to infinity.
Ionization energy = 0-(-13.6ev)=13.6ev
Ionization potential = 13.6ev

4.How are different series in hydrogen spectra originated?

ans: 
Simple reason is that different series in the hydrogen spectra is originated when the electron jumps from stationery orbit of higher energy to lower energy.

5.An electron is in the third excited state.How many different photon wavelength are possible?

ans:

Let us consider the energy of the electron in ground state be   E1,E2E3andE4${\mathrm{E}}_1,{\mathrm{E}}_2{\mathrm{E}}_3\mathrm{a}\mathrm{n}\mathrm{d}{\mathrm{E}}_4$

 The possible transition in 3rd excited state  areE4→E1,E4→E2,E4→E3E3→E2,E3→E1,E2→E1${\mathrm{E}}_4\to {\mathrm{E}}_1,{\mathrm{E}}_4\to {\mathrm{E}}_2,{\mathrm{E}}_4\to {\mathrm{E}}_3{\mathrm{E}}_3\to {\mathrm{E}}_2,{\mathrm{E}}_3\to {\mathrm{E}}_1,{\mathrm{E}}_2\to {\mathrm{E}}_1$ therefore 6 different wavelength are possible when the electron is in 3rd excited state.

6.How many lines can be drawn in the energy level diagram of hydrogen atom?

ans:

The number of the transition to the state n = 1 from the higher states other than n=1  is (n-1). Similarly The number of the transition to the state n = 2 from the higher states other than n=2  is (n-2) and so on. The total number of lines is therefore N = (n-1) + (n-2) +..[ n- (n-1)] = 12n(n−1)$\frac{1}{2}\mathrm{n}\left(\mathrm{n}-1\right)$

7.Point out the differences between matter wave and electromagnetic wave.

ans:

Matter wave	Electromagnetic wave
1. Matter wave was produced when a particle of mass m moves.	1. The electromagnetic waves are produced when charge particle are accelerated.
2. The velocity of matter wave depends upon the velocity of the matter in motion.	2. The velocity of electromagnetic wave is independent of the motion of the medium and is constant in medium.

8.What is an electron microscope?

ans:

An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects.