A radio transmitter operates at a frequency 880 kHz and a power of 10 kW. The number of photons emitted per second is
The valence electron in alkali metal is a
f-electron
p-electron
s-electron
d-electron
The nuclei and can be described as
Isotopes of nitrogen
Isotones
Isobars
Isotopes of carbon
Which of the following statements is true for nuclear forces ?
They obey the inverse square law of distances
They obey the inverse third power law of distance
They are short range forces
They are equal in strength to electromagnetic forces.
The ratio of the radii of the nuclei and approximately
The constituents of atomic nuclei are believed to be
Neutrons and protons
Protons only
Electrons and protons
Electrons, protons and neutrons.
The halflife of radium is 1600 years, the fraction of a sample of radium that would remain after 6400 years
1/4
1/2
1/8
1/16
An electron with (rest mass moves with a speed of 0.8 c. Its mass when its moves with this speed is
In the nucleus of , the number of protons, neutrons and electrons are
The ground state energy of H-atom 13.6 eV. The energy needed to ionize H-atom from its second excited state.
1.51 eV
3.4 eV
13.6 eV
12.1 eV
In terms of Bohr radius , the radius of the second Bohr orbit of a hydrogen atom is given by
Solar energy is due to
Fusion reaction
Fission reaction
Combustion reaction
Chemical reaction
The ionization energy of hydrogen atom is 13.6 eV. Following Bohr’s theory, the energy corresponding to a transition between 3rd and 4th orbit is
3.40 eV
1.51 eV
0.85 eV
0.66 eV
Solar energy is due to
Fusion reaction
Fission reaction
Combustion reactions
Chemical reactions
The mass density of a nucleus varies with mass number A as
A
Constant
1/A
When light of wavelength 300 nm (nanometer) falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, however, light of 600 nm wavelength is sufficient for creating photoemission. What is the ratio of the work functions of the two emitters ?
1 : 2
2 : 1
4 : 1
1 : 4
Number of ejected photoelectron increases with increases
In intensity of light
In wavelength of light
Infrequency of light
Never
Solid forms
Ionic bond
Vander Waal bond
Chemical bond
Covalent bond
The binding energy per nucleon is maximum in case is
Which source is associates with a line emission spectrum ?
Electric fire
Neon street sign
Red traffic light
Sun