Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NEET2007PhysicsDual Nature of MatterActual

A 5 watt source emits monochromatic light of wavelength 5000 Å . When placed 0.5 ~m away, it liberates photoclectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0 ~m , the number of photoelectrons liberated will be reduced by a factor of :

Options

  1. A8
  2. B16
  3. C2
  4. D4

Correct answer

D. 4

Step-by-step solution

Intensity is given by I= p 4 d^2 where p= power of source d= distance We know (assume) that light to spread out uniformly is all direction i.e. spherical source. aligned & I 1 d^2 or I₁ I₂ = d₂^2 d₁^2 & or I₁ I₂ = ( 1 0.5 )^2 & I₁ I₂ =4 & or I₂= I₁ 4 aligned

Practice Dual Nature of Matter on Quantrex Academy →

More from Dual Nature of Matter

An electron and positron are accelerated from rest to the same kinetic energy. The ratio of their de Broglie wavelengths is 2026An electron of mass m and charge e initially at rest gets accelerated by a constant electric field E. The de-Broglie wavelength of the electron at time t is (h = Planck's constant) 2026The wavelength _e of an electron and _P of a photon of same energy E are related as 2026A light of wavelength ( < ₀) falls on a metal surface. The momentum of the fastest moving electron is p . In order to have the momentum of an electron equal to 2p , the required wa 2026The de Broglie wavelength of an electron with kinetic energy K₁ is ₁ . If the kinetic energy increases to 5K₁ , the new wavelength is ₂ = x ₁ . The value of x is 2026A student plots two different graphs using the same photoelectric experiment data. 1. Maximum kinetic energy ( K_ max ) against frequency ( ) 2. Stopping potential ( V_o ) against 2026In a photoelectric cell, for the incident radiation of wavelength , the fastest electron has speed 'v'. If the wavelength of incident radiation is changed to 3 , the speed of the f 2026A particle is dropped from a height ' y '. The de-Broglie wavelength of the particle as a function of height is 2026 Full Dual Nature of Matter list All NEET PYQs