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
Einstein's work on photoelectric effect gives support to
E = mc2
E = hν
hν = 1/2 mv2
E = h/λ
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.
An electron is accelerated through a potential difference of 1000 volt. Velocity is nearly
3.8 × 107 m s-1
1.9 × 106 m s-1
1.9 × 107 m s-1
5.7 × 107 m s-1
Which of the following are thermions?
protons
electrons
photons
positrons
Light of wavelength 4000 angstrom is incident on a sodium surface for which the threshold wavelength of photoelectrons is 5420 angstrom. The work function is
4.58 electron volt
2.31 electron volt
1.14 electron volt
0.57 electron volt
Three-fourths of the active nuclei present in a radioactive sample decay in 3/4 s. The half-life of the sample is
1 s
½ s
¾ s
3/8 s
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
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
When ultraviolet rays are incident on metal plate,the photoelectric effect does not occur.It occurs by incidence of
infrared rays
X -rays
radiowaves
light waves
