In a certain region of space electric file and magnetic field are perpendicular to each other and an electron enters in region perpendicular to the direction of and both and moves undeflected, then velocity of electron is
Which of the following is the longest wave?
Ozone layer blocks the radiations of wave length
less than 3 × 10-7 m
equal to 3 × 10-7 m
more than 3 × 10-7 m
all of the above
The frequency of electromagnetic wave, which is best suited to observe a particle of radius 3 × 10-4 cm, is of the order of
Which of the following has minimum wavelength?
X-rays
Ultraviolet rays
y-rays
Cosmic rays
The velocity of electromagnetic radiation in a medium of permittivity ε0 and permeability μ0 is given by
The amplitudes of electric and magnetic fields in an electromagnetic wave are related to each other as
E0 = B0
E0 = cB0
E0 = B0 /c
E0 = c/B
The frequency of y-rays, X-rays and ultraviolet rays are a, b and c respectively. Then
The ground state energy H-atom is 13.6 eV. The energy needed to ionize H –atom from its second excited state is
1.51 eV
3.4 eV
13.6 eV
12.1 eV
Which of the following rays are not electromagnetic waves?
β-rays
Heat rays