When ultraviolet rays are incident on metal plate,the photoelectric effect does not occur.It occurs by incidence of
infrared rays
X -rays
radio waves
light waves
Which one of the following statements is wrong in the context of X-rays generated from an X-ray tube?
Wavelength of characteristic X-rays decreases when the atomic number of the target increases.
Cut-off wavelength of the continuous X-rays depends on the atomic number of the target.
Intensity of the characteristic X-rays depends on the electrical power given to the X-ray tube.
Cut-off wavelength of the continuous X-rays depends on the energy of the X-ray tube.
In the phenomenon of electric discharge through gases at low pressure,the coloured glow in the tube appears as a result of
excitation of electrons in the atoms
collision between the atoms of the gas
collisions between the charged particles emitted from the cathode and the atoms of the gas
collision between different electrons of the atoms of the gas
Bragg's equation will have no solution, if
λ > 2d
λ < 2d
λ < d
λ = d
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
When an electron in the hydrogen atom jumps from the 2nd orbit to the 1st orbit, the wavelength of the radiation emitted is λ. When an electron jumps from 3rd orbit to 1st orbit, the wavelength of emitted radiation would be
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
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
Which of the following are thermions?
protons
electrons
photons
positrons
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
