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STD 11 - 2. structure of atom — NEET STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceNEETSTD 11 - 2. structure of atom4 Marks
MCQ
Given below are two statements : one is labelled as Assertion $A$ and the other is labelled as Reason $R$:

Assertion $A$: In the photoelectric effect, the electrons are ejected from the metal surface as soon as the beam of light of frequency greater than threshold frequency strikes the surface.

Reason $R$ : When the photon of any energy strikes an electron in the atom, transfer of energy from the photon to the electron takes place.

In the light of the above statements, choose the most appropriate answer from the options given below :

  • A
    Both $A$ and $R$ are correct but $R$ is NOT the correct explanation of $A$
  • ✓
    $A$ is correct but $R$ is not correct
  • C
    Both $A$ and $R$ are correct and $R$ is the correct explanation of $A$
  • D
    $A$ is not correct but $R$ is correct
✓

Answer

Correct option: B.
$A$ is correct but $R$ is not correct
b
There is a characteristic minimum frequency, or "threshold frequency," for each metal below which the photoelectric effect is not seen. The ejected electrons leave with a specific amount of kinetic energy at a frequency $v > v _0$ with an increase in light frequency of these electron kinetic energies also rise.

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