Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Dual Nature of Radiation question

2011 · Shift 0 · Q53
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Physics
  4. /Dual Nature of Radiation
  5. /2011 · Shift 0 · Q53

Dual Nature of Radiation question

2011 · Shift 0 · Q53

JEE MainPhysicsDual Nature of RadiationMCQ+4 / −1
This question has Statement - 111 and Statement -222. Of the four choices given after the statements, choose the one that best describes the two statements. Statement - 111: A metallic surface is irradiated by a monochromatic light of frequency v>v0v \gt {v_0}v>v0​(the threshold frequency). The maximum kinetic energy and the stopping potential are Kmax⁡{K_{\max }}Kmax​ and V0{V_0}V0​ respectively. If the frequency incident on the surface is doubled, both the Kmax⁡{K_{\max }}Kmax​ anmd V0{V_0}V0​ are also doubled. Statement -222 : The maximum kinetic energy and the stopping potential of photoelectrons emitted from a surface are linearly dependent on the frequency of incident light.
  1. A
    Statement - 111 is true, Statement -222 is true, Statement -222 is the correct explanation of Statement -111.
  2. B
    Statement - 111 is true, Statement -222 is true, Statement -222 is not the correct explanation of Statement -111.
  3. C
    Statement - 111 is false, Statement -222 is true.
  4. D
    Statement - 111 is true, Statement -222 is false.
View written solutionFree

Correct answer: C

  1. Use Einstein’s photoelectric equation

    For incident light of frequency ν\nuν on a metal of threshold frequency ν0\nu_0ν0​, Kmax⁡=hν−hν0=h(ν−ν0).K_{\max} = h\nu - h\nu_0 = h(\nu-\nu_0).Kmax​=hν−hν0​=h(ν−ν0​).

    Also, stopping potential VsV_sVs​ is related by eVs=Kmax⁡⇒Vs=Kmax⁡e=he(ν−ν0).eV_s = K_{\max} \quad \Rightarrow \quad V_s = \frac{K_{\max}}{e} = \frac{h}{e}(\nu-\nu_0).eVs​=Kmax​⇒Vs​=eKmax​​=eh​(ν−ν0​).

  2. Check Statement-1

    Initially, Kmax⁡=h(ν−ν0).K_{\max} = h(\nu-\nu_0).Kmax​=h(ν−ν0​).

    If the frequency is doubled, ν→2ν\nu \to 2\nuν→2ν, then Kmax⁡′=h(2ν−ν0).K'_{\max} = h(2\nu-\nu_0).Kmax′​=h(2ν−ν0​).

    For Statement-1 to be true, we would need Kmax⁡′=2Kmax⁡.K'_{\max} = 2K_{\max}.Kmax′​=2Kmax​.

    But 2Kmax⁡=2h(ν−ν0)=h(2ν−2ν0),2K_{\max} = 2h(\nu-\nu_0)=h(2\nu-2\nu_0),2Kmax​=2h(ν−ν0​)=h(2ν−2ν0​), whereas Kmax⁡′=h(2ν−ν0).K'_{\max}=h(2\nu-\nu_0).Kmax′​=h(2ν−ν0​).

    These are not equal in general.

    In fact, Kmax⁡′−2Kmax⁡=hν0≠0.K'_{\max}-2K_{\max}=h\nu_0 \neq 0.Kmax′​−2Kmax​=hν0​=0.

    So Kmax⁡K_{\max}Kmax​ does not double.

    Since Vs=Kmax⁡e,V_s = \frac{K_{\max}}{e},Vs​=eKmax​​, stopping potential also does not double in general.

    Therefore, Statement-1 is false.

  3. Check Statement-2

    From the equations, Kmax⁡=hν−hν0,K_{\max} = h\nu - h\nu_0,Kmax​=hν−hν0​, which is linear in ν\nuν.

    Also, Vs=heν−hν0e,V_s = \frac{h}{e}\nu - \frac{h\nu_0}{e},Vs​=eh​ν−ehν0​​, which is also linear in ν\nuν.

    Therefore, Statement-2 is true.

  4. Choose the correct option

    • Statement-1: False
    • Statement-2: True

    Hence, the correct option is: C\boxed{\text{C}}C​

PreviousNext

More from Dual Nature of Radiation

  • If a source of power 4kW produces 1020 photons/second, the radiation belongs to a part of the spectrum called2010 · MCQ
  • Statement - 1: When ultraviolet light is incident on a photocell, its stopping potential is V0​ and the maximum kinetic energy of the photoelectrons is Kmax​. When the ultraviolet light is replaced by X-rays, both V0​…2010 · MCQ
  • The surface of a metal is illuminated with the light of 400nm. The kinetic energy of the ejected photoelectrons was found to be 1.68eV. The work function of the metal is : (hc=1240eV.nm)2009 · MCQ
  • In an experiment, electrons are made to pass through a narrow slit of width ′d′ comparable to their de Broglie wavelength. They are detected on a screen at a distance ′D′ from the slit (see figure). Which of the following graphs can be… Includes diagram2008 · MCQ
  • Photon of frequency v has a momentum associated with it. If c is the velocity of light, the momentum is2007 · MCQ
  • The anode voltage of a photocell is kept fixed. The wavelength λ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows2006 · MCQ
  • The threshold frequency for a metallic surface corresponds to an energy of 6.2eV and the stopping potential for a radiation incident on this surface is 5V. The incident radiation lies in2006 · MCQ
  • The time taken by a photoelectron to come out after the photon strikes is approximately2006 · MCQ