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Modern Physics Test - 5
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  • Question 1/10
    4 / -1

    A 280 days old radioactive substance shows an activity of 6000 dps, 140 days later its activity becomes 3000 dps.
    What was its initial activity?

  • Question 2/10
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    A pr oton has kinetic ener gy E = 100 keV which is equal to that of a photon. The wavelength of photon is λ2 and that of proton is λ1. The ration of λ2/λ1 is proportional to 

  • Question 3/10
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    Kα wavelength emitted by an atom  of atomic number Z = 11 is λ. Find the atomic number for an atom that emits Kα radiation with wavelength 4λ.

  • Question 4/10
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    A photon collides with a stationary hydrogen atom in ground state inelastically. Energy of the colliding photon is 10.2 eV.
    After a time interval of the order of micro second another photon collides with same hydrogen atom inelastically with an energy of 15 eV. What will be observed by the detector?

  • Question 5/10
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    A beam of electron is used in an YDSE experiment. The slit width is d. When the velocity of electron is increased, then

  • Question 6/10
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    If a star can convert all the He nuclei completely into oxygen nuclei, the energy released per oxygen nuclei is  [Mass of He nucleus is 4.0026 amu and mass of Oxygen nucleus is 15.9994 amu]

  • Question 7/10
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     is a radioactive substance having half life of 4 days. Find the probability that a nucleus undergoes decay after two half lives

  • Question 8/10
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    In the options given below, let E denote the rest mass energy of a nucleus and n a neutron.The correct option is

  • Question 9/10
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    The largest wavelength in the ultraviolet region of the hydrogen spectrum is 122 nm. The smallest wavelength in the infrared region of the hydrogen spectrum (to the nearest integer) is

  • Question 10/10
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    Electrons with de-Broglie wavelength λ fall on the target in an X-ray tube. The cut-off wavelength of the emitted X-rays is

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