RankLab
Back to Questions
ChemistryHardMCQ2015 ยท 11 Apr Online

Q34.At temperature T , the average kinetic energy of any particle is 32 kT. The de Broglie wavelength follows the order: (1) Visible photon >thermal electron >thermal (2) Thermal neutron >visible photon >thermal neutron. electron. (3) Thermal neutron >thermal electron >visible (4) Visible photon >thermal neutron >thermal photon. electron.

What This Question Tests

This multi-concept question requires comparing the de Broglie wavelengths of thermal electrons and neutrons with the wavelength of a visible photon, applying formulas for kinetic energy, momentum, and photon energy.

Concepts Tested

De Broglie wavelengthKinetic energy of thermal particlesEnergy of a photonParticle mass

Formulas Used

ฮป = h/p

p = sqrt(2mK)

K = (3/2)kT

E = hc/ฮป

๐Ÿ“š NCERT Sections This Tests

12.8 โ€” A 12.5 Ev Electron Beam Is Used To Bombard Gaseous Hydrogen At

Physics Class 12 ยท Chapter 12

78% match

12.8 A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. What series of wavelengths will be emitted?

12.5 โ€” A Hydrogen Atom Initially In The Ground Level Absorbs A Photon,

Physics Class 12 ยท Chapter 12

78% match

12.5 A hydrogen atom initially in the ground level absorbs a photon, which excites it to the n = 4 level. Determine the wavelength and frequency of photon.

11.4 โ€” Monochromatic Light Of Wavelength 632.8 Nm Is Produced By A

Physics Class 12 ยท Chapter 11

77% match

11.4 Monochromatic light of wavelength 632.8 nm is produced by a helium-neon laser. The power emitted is 9.42 mW. (a) Find the energy and momentum of each photon in the light beam, (b) How many photons per second, on the average, arrive at a target irradiated by this beam? (Assume the beam to have uniform cross-section which is less than the target area), and (c) How fast does a hydrogen atom have to travel in order to have the same momentum as that of the photon?