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We sidh to see inside an atom.Assuming the atom to have a diameter of 100 pm[ 1 pictomerer(pm) = `10^(-12) m`],this means that one must be able to resolve a width of say 10 pm.If an electron micriscope is used,the minimum electron energy required is about

A

1.5 keV

B

15 keV

C

150 keV

D

1.5 MeV

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The existence of negatively charged particle in an atom was shown by J.J. Thomson as a result of the studies of the passage of electricity through gases at extremely low pressure known as discharge tube experiments. When a high voltage of the order of 10,000 volts or more was impressed across the electrodes, some sort of invisible rays moved from the negative electrode to the positive electrode these rays are called as cathode rays. Cathode rays travel in straight path in absence of electrical and magnetic field . Cathode rays consist of material part and charged particles? Cathode rays produce X-rays and light is emitted when they strike on ZnS screen. Cathode rays penetrate through thin sheets of aluminium and other metals . They affect the photogenic plate and passes heating effect when they strike on metal foil. The raito of charge to mass i.e charge/mass is same for all the cathode rays irrespective of the gas used in the tube. The existence of positively charged particle in an atom was shown be E. Goldstein. He repeated the same discharge tube experiments by using a perforated cathode. It was observed that when a high potential difference was applied between the electrodes, not only cathode rays were produced but also a new type of rays were produced simultaneoulsy from anode moving towards cathode and passes through the holes or canal of the cathode. These termed as canal rays or anode rays. These rays travel in straight lines and consists of positively charged particles. These rays have kinetic energy and produces heating effect also. The e/m ratio of these rays is smaller than that of electrons. Unlike cathode rays, their e/m value is dependent upon the nature of the gas taken in the tube. These rays produced flashes of light on ZnS screen and can pass throughs thin metal foils. They can produce physical and chemical changes and are capable to produce ionisation in gases. For cathode rays the value of e/m:

The existence of negatively charged particle in an atom was shown by J.J. Thomson as a result of the studies of the passage of electricity through gases at extremely low pressure known as discharge tube experiments. When a high voltage of the order of 10,000 volts or more was impressed across the electrodes, some sort of invisible rays moved from the negative electrode to the positive electrode these rays are called as cathode rays. Cathode rays travel in straight path in absence of electrical and magnetic field . Cathode rays consist of material part and charged particles? Cathode rays produce X-rays and light is emitted when they strike on ZnS screen. Cathode rays penetrate through thin sheets of aluminium and other metals . They affect the photogenic plate and passes heating effect when they strike on metal foil. The raito of charge to mass i.e charge/mass is same for all the cathode rays irrespective of the gas used in the tube. The existence of positively charged particle in an atom was shown be E. Goldstein. He repeated the same discharge tube experiments by using a perforated cathode. It was observed that when a high potential difference was applied between the electrodes, not only cathode rays were produced but also a new type of rays were produced simultaneoulsy from anode moving towards cathode and passes through the holes or canal of the cathode. These termed as canal rays or anode rays. These rays travel in straight lines and consists of positively charged particles. These rays have kinetic energy and produces heating effect also. The e/m ratio of these rays is smaller than that of electrons. Unlike cathode rays, their e/m value is dependent upon the nature of the gas taken in the tube. These rays produced flashes of light on ZnS screen and can pass throughs thin metal foils. They can produce physical and chemical changes and are capable to produce ionisation in gases. Which is not true with respect to cathode rays?

The existence of negatively charged particle in an atom was shown by J.J. Thomson as a result of the studies of the passage of electricity through gases at extremely low pressure known as discharge tube experiments. When a high voltage of the order of 10,000 volts or more was impressed across the electrodes, some sort of invisible rays moved from the negative electrode to the positive electrode these rays are called as cathode rays. Cathode rays travel in straight path in absence of electrical and magnetic field . Cathode rays consist of material part and charged particles? Cathode rays produce X-rays and light is emitted when they strike on ZnS screen. Cathode rays penetrate through thin sheets of aluminium and other metals . They affect the photogenic plate and passes heating effect when they strike on metal foil. The raito of charge to mass i.e charge/mass is same for all the cathode rays irrespective of the gas used in the tube. The existence of positively charged particle in an atom was shown be E. Goldstein. He repeated the same discharge tube experiments by using a perforated cathode. It was observed that when a high potential difference was applied between the electrodes, not only cathode rays were produced but also a new type of rays were produced simultaneoulsy from anode moving towards cathode and passes through the holes or canal of the cathode. These termed as canal rays or anode rays. These rays travel in straight lines and consists of positively charged particles. These rays have kinetic energy and produces heating effect also. The e/m ratio of these rays is smaller than that of electrons. Unlike cathode rays, their e/m value is dependent upon the nature of the gas taken in the tube. These rays produced flashes of light on ZnS screen and can pass throughs thin metal foils. They can produce physical and chemical changes and are capable to produce ionisation in gases. Select the incorrect statement.

classically an electron can be in any orbit around nucleus of an atom. Then what determines the typical atomic size? Why is an atom not, say, thousand times bigger than its typical size? Thequestion had greatly puzzled Bohr before he arrived at his famous model of the atom that you have learnt in the text. To simulate what he might well have done before his discovery, let us play as followswith the basic constants of nature e, me, c and see if we can get a quantity with the dimensions of length that is roughly equal to the known size of an atom (~ 10 m).- You will find that the length obtained above is many orders of magnitude smaller than the atomic dimensions. Further, it involves c. But energies of atoms are mostly in non-relativistic domain where c is not expected to play any role. This is what may have suggested Bohr to discard c and look for else h had already made its appearance elsewhere. Bohr lay in recognising that h, m_e , and e will yield the right atomic size. Construct a quantity with the dimension of length from h, me, and e and confirm that its numerical value has indeed the correct order of magnitude.

A parallel plate capacitor is to be designed with a voltage rating 1 kV, using a material of dielectric constant 3 and dielectric strength about 10^7 Vm^-1 . (Dielectric strength is the maximum electric field a material can tolerate without breakdown, i.e., without starting to conduct electricity through partial ionisation.) For safety, we should like the field never to exceed, say 10% of the dielectric strength. What minimum area of the plates is required to have a capacitance of 50 pF?

Classically, an electron can be in any orbit around the nucleus of an atom. Then what determines the typical atomic size? Why is an atom not, say, thousand times bigger than its typical size? The question had greatly puzzled Bohr before he arrived at his famous model of the atom that you have learnt in the text. To simulate what he might well have done before his discovery, let us play as follows with the basic constants of and see if we can get a quantity with the dimensions of length that is roughly equal to the known of an atom (~ 10^ -10 m).- Construct a quantity with the dimensions of length from the fundamental constants e, m_e , and c. Determine its numerical value.

A copper atom consists of copper nucleus surrounded by 29 electrons. The atomic weight of copper is 63.5mol e^(-1) . Let us now take two pieces of copper each weighing 10g. Let us trandfer one elcetron from one piece to another for every 100 atoms in that piece. What will be the Coulomb force between the two pieces after the trandfer of electrons, if they are 1cm apart? Avogadro number= 6xx10^(23) mol e^(-1) , charge on an electron =- 1.6xx10^(-19)C.

If hydrogen atoms (in the ground state ) are passed through an homogeneous magnetic field, the beam is split into two parts. This interaction with the magnetic field shows that the atoms must have magnetic moment. However, the moment cannot be due to the orbital angular momentum since l=0. Hence one must assume existence of intrinsic angular momentum, which as the experiment shows, has only two permitted orientations. Spin of the electron produce angular momentum equal to S=sqrt(s(s+1))(h)/(2pi) where S=+(1)/(2) . Total spin of an atom = +(n)/(2) " or "-(n)/(2) where n is the number of unpaired electrons. The substance which contain species with unpaired electrons in their orbitals behave as paramagnetic substances. The paramagnetism is expressed in terms of magnetic moment. The magnetic moment of an atom mu_(s)sqrt(s(s+1))(eh)/(2pimc)=sqrt((n)/(2)((n)/(2)+1))(eh)/(2pimc)" "s=(n)/(2) impliesmu_(s)=sqrt(n(n+1)) B.M. 1. B.M. (Bohr magneton)= (eh)/(4pimc) If magnetic moment is zero the substance is diamagnetic. If an ion of _(25)Mn has a magnetic moment of 3.873 B.M. Then oxidation state of Mn in ion is :

If hydrogen atoms (in the ground state ) are passed through an homogeneous magnetic field, the beam is split into two parts. This interaction with the magnetic field shows that the atoms must have magnetic moment. However, the moment cannot be due to the orbital angular momentum since l=0. Hence one must assume existence of intrinsic angular momentum, which as the experiment shows, has only two permitted orientations. Spin of the electron produce angular momentum equal to S=sqrt(s(s+1))(h)/(2pi) where S=+(1)/(2) . Total spin of an atom = +(n)/(2) " or "-(n)/(2) where n is the number of unpaired electrons. The substance which contain species with unpaired electrons in their orbitals behave as paramagnetic substances. The paramagnetism is expressed in terms of magnetic moment. The magnetic moment of an atom mu_(s)sqrt(s(s+1))(eh)/(2pimc)=sqrt((n)/(2)((n)/(2)+1))(eh)/(2pimc)" "s=(n)/(2) impliesmu_(s)=sqrt(n(n+1)) B.M. 1. B.M. (Bohr magneton)= (eh)/(4pimc) If magnetic moment is zero the substance is diamagnetic. Which of the following ion has lowest magnetic moment?

Are the nucleons fundamental particles, or do they consist of still smaller parts? One way to find out is probe a nucleon just as Rutherford probed an atom. What should be the kinetic energy of an electron for it to be able to probe a nucleon? Assume the diameter of a nucleon to be approximately 10^-15m .

MODERN PUBLICATION-UNIT TEST -07-EXERCISE
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  2. Hard X-rays for the studdy of fractures in bones shjold have a minimum...

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  3. We sidh to see inside an atom.Assuming the atom to have a diameter of ...

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  4. Directions.In the following question, a statement of asertion followed...

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  5. Directions.In the following question, a statement of asertion followed...

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  6. Directions.In the following question, a statement of asertion followed...

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  7. Directions.In the following question, a statement of asertion followed...

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  8. Directions.In the following question, a statement of asertion followed...

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  9. Directions.In the following question, a statement of asertion followed...

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  10. Directions.In the following question, a statement of asertion followed...

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  11. Directions.In the following question, a statement of asertion followed...

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  12. Directions.In the following question, a statement of asertion followed...

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  13. Directions.In the following question, a statement of asertion followed...

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  14. Directions.In the following question, a statement of asertion followed...

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  15. Directions.In the following question, a statement of asertion followed...

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  16. Directions.In the following question, a statement of asertion followed...

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  17. Directions.In the following question, a statement of asertion followed...

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  18. What is incorrect photon?

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  19. The energy fof an X - ray photon is 2 keV,then the frequency (in per s...

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  20. Photoelectric effect demonstrate nature of radiation.

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