When the atoms in a sample of hydrogen like atoms are in the fourth (n = 4) orbit, how many spectral lines will be emitted in the radiation spectrum of the sample?
4
5
6
9
The de - Broglie wave corresponding to a particle of mass m and velocity v has a wavelength associated with it is
h/mν
hmν
mh/ν
m/hν
Monochromatic light incident on a metal surface emits electrons with kinetic energies from 0 to 2.6 eV. What is the least energy of the incident photon, if the tightly bound electrons needs 4.2 eV to remove?
1.6 eV
Between 1.6 eV and 6.8 eV
6.8 eV
More than 6.8 eV
A radiotransmitter operates at a frequency 1000 kHz and a power of 66 kW. Find the number of photons emitted per second.
1027
1028
1029
1030
Gases begin to conduct electricity at low pressure because
at low pressures gases turn to plasma
colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionisation of atoms
atoms break up into electrons and protons
the electrons in atoms can move freely at low pressures
Which of the following are thermions?
protons
electrons
photons
positrons
A photon of energy 10.2 eV corresponds to light of wavelength λ0. Due to an electron transition from n = 2 to n = 1 in a hydrogen atom, light of wavelength λ is emitted. If we take into account the recoil of an atom, when a photon is emitted,
λ = λ0
λ < λ0
λ > λ0
The data is not sufficient to reach a conclusion.
Bragg's equation will have no solution, if
λ > 2d
λ < 2d
λ < d
λ = d
If the wavelength of Hα line of the Balmer series of the hydrogen spectum is λ the wavelength of the
Hβ line is 7/20 λ
Least energetic spectral line of the Lyman series is 5/27 λ
Ionisation potential of hydrogen is hc/λ
All the above are true
If h is Planck's constant, the momentum of a photon of wavelength 0.01 Å is
h × 10-2
h
h × 102
h × 1012