Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main20199 Jan 2019Morning ShiftPhysicsDual Nature of MatterActual

The surface of certain metal is first illuminated with light of wavelength λ 1 = 350 n m and then, by a light of wavelength λ 2 = 540 n m . It is found that the maximum speed of the photoelectrons in the two cases differ by a factor of 2 . The work function of the metal (in e V ) is close to (Energy of photon = 1240 λ i n n m e V )

Options

  1. A2.5
  2. B1.8
  3. C5.6
  4. D1.4

Correct answer

B. 1.8

Step-by-step solution

λ 1 = 350  n m ,    λ 2 = 540   n m ,     V 1 V 2 = 2 ⇒ V 1 = 2 V   a n d   V 2 = V h c λ 1 = ϕ + 1 2 m 2 V 2 h c λ 2 = ϕ + 1 2 m V 2 h c λ 1 - 4 h c λ 2 = ϕ - 4 ϕ h c 4 540 - 1 340 = 3 ϕ ϕ = 1.8   e V

Practice Dual Nature of Matter on Quantrex Academy →

More from Dual Nature of Matter

K₁ and K₂ be the maximum kinetic energies of photoelectrons emitted from a surface of a given material for the light of wavelength ₁ and ₂ , respectively. If ₁=2 ₂ then the work fu 2026The de Broglie wavelength for an electron accelerated through the potential difference of V₁ volt is ₁ . When the potential difference is changed to V₂ volt, the associated de Brog 2026Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The electromagnetic wave exerts pressure on the surface on 2026An electron is travelling with a velocity v in free space and when it enters a medium, its velocity is reduced by 20 % . The de Broglie wavelength of electron in the medium is ₀ , 2026An electron of mass m is moving in an electric field E = -2E₀ i ( E₀ = constant > 0 ), with an initial velocity V = v₀ i ( v₀ = constant > 0 ). If ₀ = h 4mv₀ , its de Broglie wavel 2026Light source having wavelength 331 nm is used to generate photo-electrons whose stopping potential is 0.2 V. The work function of the used metal in the experiment is 10⁻¹⁹ J. The v 2026Match the List-I with List-II List-I List-II A. Planck's constant I. ML^2T⁻² B. Stopping potential II. T⁻¹ C. Work function III. ML^2T⁻¹ D. Threshold frequency IV. ML^2T⁻³A⁻¹ Choos 2026The de Broglie wavelength associated with an electron accelerated through a potential difference V is _e and the de Broglie wavelength associated with a proton accelerated through 2026 Full Dual Nature of Matter list All JEE Main PYQs