ICS Part 2 Physics Chapter 20 Short Questions Preparation

Question # 1

Define population inversion and metastable stable.

Ans 1: A condition of matter in which more electrons are in a high energy state than in a lower energy state is called population inversion.
A particular excited state of an atom that has longer lifetime than the ordinary excited states is called metastable state.

Question # 2

Distinguished between stimulated emission and spontaneous emission.

Ans 1: Stimulated emission: If a atom is excited for a longer lifetime of about 10^-3sec than an incident photon of energy equal to the difference of two energy levels induces the atom to decay by emitting a photon that travel in the direction of incident photon.This process is called stimulated or induced emission.
Ans 2: Spontaneous Emission: As excited is highly unstable with life time of
10^-8sec,so electron will de excite itself with emission of a photon in any arbitrarydirection is called spontaneous emission.

Question # 3

What is fluorescence?

Ans 1: Fluorescence is a property of absorbing radiant energy of high frequency and re emitting energy of low frequency in the visible region of electromagnetic spectrum.

Question # 4

What is meant by line spectrum? How line spectrum can be used for the identification of elements?

Ans 1: When an electron jumps from higher energy state to lower energy state than emits energy and make a spectral line.
E₂- E₁_=hf
_{This is called line spectrum.And different elements emit line spectrum of different wavelengths,So they can be identifiedeasily.}

Question # 5

Give two uses of laser in medicine and industry.

Ans 1: Laser is used
1. For welding detached retinas
2. To destroy cancerous and precancerous cells.

Question # 6

Write down use of laser in industry.

Ans 1: It can be used for telecommunication in fibre optics.
It is used to read bar codes,
It is used to generate 3D image of objects by holography.

Question # 7

What do you mean by inner shell transition?

Ans 1: A transition in which an electron from higher orbit,emits energy and accommodate a hole in the lower orbit.Such a transition is called inner shell transition.The photons emitted in such transition are called characteristic x-rays.

Question # 8

How can spectrum of hydrogen contain so many lines,whereas hydrogen atom contain one electron?

Ans 1: The single electron in hydrogen atom occupies ground state but it can be excited to several states by absorbing energy.During de-excitation ,it can emit several lines of different wavelength.

Question # 9

What are the difference between laser light and ordinary light?

Ans 1: The laser light is intense ,unidirectional and phase coherent ,so it does bit spread as compared to ordinary light.
The energy of laser can be focused at a point to get enough heat for welding which is not possible with ordinary light.
A laser beam is used as a surgical tool for welding detached retina which ordinary light can not do.

Question # 10

Define continuous spectrum.

Ans 1: The radiation emitted by continuous media such as ''Black Body" forms a continuous spectrum,In continuousspectrum wavelengths of radiations can not be observed in discrete lines.

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ICS Part 2 Physics Chapter 20 Short Questions Preparation

12th Class PhysicsShort Questions Preparation

12th Class Physics Chapter Wise Preparation

Online Short Questions For Chapter 9 "ICS Part 2 Physics Chapter 20 Short Questions Preparation "

Physics - ICS Part 2 Physics Chapter 20 Short Questions Preparation

Define population inversion and metastable stable.

Distinguished between stimulated emission and spontaneous emission.

What is fluorescence?

What is meant by line spectrum? How line spectrum can be used for the identification of elements?

Give two uses of laser in medicine and industry.

Write down use of laser in industry.

What do you mean by inner shell transition?

How can spectrum of hydrogen contain so many lines,whereas hydrogen atom contain one electron?

What are the difference between laser light and ordinary light?

Define continuous spectrum.

Prepare Complete Set Wise Questions For Chapter 9 "ICS Part 2 Physics Chapter 20 Short Questions Preparation "

Set 1

Set 2

Set 3

ICS Part 2 Physics Chapter 20 Short Questions Preparation - Set 1

Define population inversion and metastable stable.

Distinguished between stimulated emission and spontaneous emission.

What is fluorescence?

What is meant by line spectrum? How line spectrum can be used for the identification of elements?

Give two uses of laser in medicine and industry.

Write down use of laser in industry.

What do you mean by inner shell transition?

How can spectrum of hydrogen contain so many lines,whereas hydrogen atom contain one electron?

What are the difference between laser light and ordinary light?

Define continuous spectrum.

ICS Part 2 Physics Chapter 20 Short Questions Preparation - Set 2

Explain why laser action could not occur without population inversion between atomic levels?

Bohr's theory of hydrogen atom is based upon several assumptions.Do any of these assumptions contradict classical physics?

What are the advantages of laser over ordinary light?

Can x-rays be reflected,diffracted polarized just like any other eaves?Explain

Write two properties of x-rays.

What do we mean when we say that the atom is excited?

what is Spectroscopy?

Write down use of laser in industry.

How can spectrum of hydrogen contain so many lines,whereas hydrogen atom contain one electron?

Differentiate between Line and Band spectrum.

ICS Part 2 Physics Chapter 20 Short Questions Preparation - Set 3

Give two uses of laser in medicine and industry.

Define population inversion and metastable stable.

List of color of line spectra of an excited hydrogen atom.

What do you mean by inner shell transition?

In which region of electromagnetic spectrum does the following series fall (a)Lyman series (b)Balmer series?

What is meant by line spectrum? How line spectrum can be used for the identification of elements?

Briefly describe continuous x-rays.

What is CAT scanner?

Write two postulate of Bohr's model of H-atom.

Can electron reside inside the nucleus?

ICS Part 2 Physics Chapter 20 Short Questions Preparation

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