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

2024 · 31 Jan · Shift 2 · Q63
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. /2024 · 31 Jan · Shift 2 · Q63

Dual Nature of Radiation question

2024 · 31 Jan · Shift 2 · Q63

JEE MainPhysicsDual Nature of RadiationMCQ+4 / −1
In a photoelectric effect experiment a light of frequency 1.5 times the threshold frequency is made to fall on the surface of photosensitive material. Now if the frequency is halved and intensity is doubled, the number of photo electrons emitted will be:
  1. A
    doubled
  2. B
    halved
  3. C
    Zero
  4. D
    quadrupled
View written solutionFree

Correct answer: C

  1. Use Einstein’s photoelectric equation

    For photoelectric emission to occur, the incident light frequency must satisfy ν≥ν0\nu \ge \nu_0ν≥ν0​ where ν0\nu_0ν0​ is the threshold frequency.

  2. Given initial frequency

    The initial frequency is ν=1.5 ν0\nu = 1.5\,\nu_0ν=1.5ν0​

  3. Frequency is halved

    New frequency: ν′=12(1.5ν0)=0.75ν0\nu' = \frac{1}{2}(1.5\nu_0) = 0.75\nu_0ν′=21​(1.5ν0​)=0.75ν0​

  4. Compare with threshold frequency

    Since 0.75ν0<ν00.75\nu_0 < \nu_00.75ν0​<ν0​ the new frequency is less than the threshold frequency.

    Therefore, no photoelectric emission takes place.

  5. Effect of doubling intensity

    Intensity affects the number of emitted electrons only if the frequency is above threshold.

    Here, the frequency is below threshold, so even if intensity is doubled, no electrons are emitted.

  6. Conclusion

    Number of photoelectrons emitted = zero.

  7. Option check

    • A: doubled ❌
    • B: halved ❌
    • C: Zero ✅
    • D: quadrupled ❌

Hence, the correct answer is C.

PreviousNext

More from Dual Nature of Radiation

  • A proton moving with one tenth of velocity of light has a certain de Broglie wavelength of λ. An alpha particle having certain kinetic energy has the same de-Brogle wavelength λ. The ratio of kinetic energy of proton and…2023 · MCQ
  • The threshold frequency of a metal is f0​. When the light of frequency 2f0​ is incident on the metal plate, the maximum velocity of photoelectrons is v1​. When the frequency of incident radiation is increased to 5f0​…2023 · MCQ
  • The kinetic energy of an electron, α-particle and a proton are given as 4 K,2 K and K respectively. The de-Broglie wavelength associated with electron (λe),α-particle ((λα)…2023 · MCQ
  • The work functions of Aluminium and Gold are 4.1 eV and and 5.1 eV respectively. The ratio of the slope of the stopping potential versus frequency plot for Gold to that of Aluminium is2023 · MCQ
  • Proton (P) and electron (e) will have same de-Broglie wavelength when the ratio of their momentum is (assume, mp​=1849 me​ ):2023 · MCQ
  • In photo electric effect A. The photocurrent is proportional to the intensity of the incident radiation B. Maximum Kinetic energy with which photoelectrons are emitted depends on the intensity of incident light. C. Max. K.E with which…2023 · MCQ
  • The de Broglie wavelength of a molecule in a gas at room temperature (300 K) is λ1​. If the temperature of the gas is increased to 600 K, then the de Broglie wavelength of the same gas molecule becomes2023 · MCQ
  • The variation of stopping potential (V0​) as a function of the frequency (v) of the incident light for a metal is shown in figure. The work function of the surface is Includes diagram2023 · MCQ