Old is Gold-Quantization of energy short answer questions.

1.

The accelerating voltage of a proton is increased to twice. How will it de Broglie wavelength change? Explain.

ans:

3.

Explain the difference between stimulated and spontaneous emission of radiation.

ans:

Stimulated Emission:

The  process of speeding up Atomic transitions to lower level it's called stimulated emission.
The emited Photon will be exactly in phase with  the incident photon.

Spontaneous emission:

An atom in an excited state goes to the ground state by emitting a photon  is called spontaneous emission.

When electron jumps from E2 to E1 state then:

          ΔE=E2-E1=hf

4.

If a proton and an electron have the same speed which has the longer the longer de Broglie wavelength. Explain.

ans:

5.

If a  hydrogen atom consists an electron, it's Spectrum consists of a large number of lines. Explain how.

ans:

There is only one electron in a hydrogen atom but that there are many energy levels in a hydrogen atom When a sufficient amount of energy is given then  electron jumps to a higher energy level and during returning back it gives Spectral series containing line.

6.

What is optical pumping in the production of laser?

ans:

Optical pumping is a process in which light is used to raise electrons from a lower energy level in an atom or molecule to a higher one. It is commonly used in laser construction, to pump the active laser medium so as to achieve population inversion.

8.

"The total energy of an electron of  an atom in an orbit  is negative". What does this negative energy indicate?

ans:

The total energy of an electron of an atom in an orbit is  negative the negative sign associated with each and every energy levels indicate the electron is bound to the nucleus.

9.

An electron and proton are accelerated through the same potential, which one has higher de-Broglie's wavelength? Justify your answer.

(here p is the momentum)

10.

An electron and proton have the same kinetic energy, which one has higher de-Broglie's wavelength? Justify your answer.

ans:

The kinetic energy=p2/2m, so p = √ 2mK. The lower mass electron has a lower momentum than the proton for the same kinetic energy, so it has a longer wavelength, λ = h/p. 

(here p is the momentum)

11.

An electron and proton have the same de-Broglie's wavelength, which one has higher Kinetic energy? Justify your answer.

ans:

:

since KE of electron=1840*KE of proton

12.

ans:

Stimulated Emission:

The  process of speeding up Atomic transitions to lower level it's called stimulated emission.
The emited Photon will be exactly in phase with  the incident photon.

Spontaneous emission:

An atom in an excited state goes to the ground state by emitting a photon  is called spontaneous emission.

When electron jumps from E2 to E1 state then:

          ΔE=E2-E1=hf

13.

An electron and proton have the same kinetic energy, which one has higher de-Broglie's wavelength? Justify your answer.

ans:

same as 10. 

14.

why is the gravitational force not taken in consideration while evaluating the energy of an electron in an atom?

ans:

since gravitational potential is extremely small so it is not taken is consideration.

17.

The wave nature of particle is not observable in daily life why?

ans:

we have

let us consider a man of 60kg moving with a spped of 1m/s

 λ=(h/60)=1.1*10^-35m

(h=6.6*10^-34)

which is very small not even detectable as a result of which wave nature of light is not observable.

20.

A stone is dropped from top of a building how does it's De-Broglie wavelength change?

ans:

As a stone falls, its velocity increases and so does its momentum. Thus, its wavelength decreases.

since, if a stone is dropped from top of a building it's de-Broglie wavelength goes on decreasing.

21.

What do you mean by ionization energy and ionization potential?

ans:

Ionization energy:

The ionization energy (IE) is qualitatively defined as the amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated gaseous atom.

Ionization potential:

the amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated gaseous atom is ionization energy and corresponding potential is called ionziation potential.

22.

What is laser? 

ans:

a device that generates an intense beam of coherent monochromatic light (or other electromagnetic radiation) by stimulated emission of photons from excited atoms or molecules. 

25.

Define population inversion and optical pumping.

ans:

Optical pumping:

Optical pumping is a process in which light is used to raise electrons from a lower energy level in an atom or molecule to a higher one. It is commonly used in laser construction, to pump the active laser medium so as to achieve population inversion.

Population inversion:

It is an important process in constructing the laser in which light is used to pump electrons to a higher energy level from low energy level.

29.

Differentiate between the 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.

32.

The wave nature of particle is not observable in daily life why?

ans:

we have

let us consider a man of 60kg moving with a spped of 1m/s

 λ=(h/60)=1.1*10^-35m

(h=6.6*10^-34)

which is very small not even detectable as a result of which wave nature of light is not observable.

34.

What do you mean by matter waves?

ans:

The wave nature or function for a material particle is called matter wave.

here,

λ=h/p

36.

Distinguish between spontaneous emission and stimulated emission.

ans:

Same as 12.

40.

What do you mean by uncertainty principle.

ans:

In quantum mechanics, the uncertainty principle, also known as Heisenberg's uncertainty principle, is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables, such as position x and momentum p, can be known.

41.

Point out the importance of De-Broglie wave.

ans:

1. The de-Broglie equation proves mathematically that a particle  behaves as a wave.

2. De Broglie's equation provides the relationship between momentum and frequency. 

42.

What do you mean by de-Broglie waves?

ans:

a hypothetical wave associated with the motion of a particle of atomicor subatomic size that describes effects such as the diffraction ofbeams of particles by crystals.

i.e.

λ=h/p

44.

An electron is in the third excited state how many different Photon-wavelengths are possible?

ans:

Let us consider the energy of the electron in ground state be   E1,E2E3andE4

 The possible transition in 3rd excited state  areE4→E1,E4→E2,E4→E3E3→E2,E3→E1,E2→E1 therefore 6 different wavelength are possible when the electron is in 3rd excited state.

46.

How paschen series is originated in Hydrogen Spectra?

ans:

we have,

so, paschen series is originated when electron jumps from (n2=4,5,6.......) to n1=3.

47. 

Differentiate between excitation potential and ionization potential.

ans:

Excitation potential:

This is the energy required in ev to excite a ground state atom to its excited state. When electrons jumps from ground level to another another energy level the corresponding energy is called  excitation potential.

Ionization potential:

The amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated gaseous atom is ionization energy and corresponding potential is called ionziation potential.

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