de Broglie wavelength λ associated with neutrons is related with absolute temperature T as
λ ∝ T
λ ∝
λ ∝
λ ∝ T2
A nucleus of mass number 220 decays by decay. The energy released in the reaction is 5 MeV. The kinetic energy of an -particle is
MeV
MeV
MeV
MeV
The wavelengths of Kα X- rays for lead isotopes Pb208 , Pb206 and Pb204 are λ1, λ2 and λ3 respectively. Then
λ2 =
λ2 = λ1 + λ3
λ2 = λ1 λ2
λ2 =
A.
λ2 =
Wavelengths of the K lines for given isotopes of lead (Pb) can be given by a general expression
where R - Rydberg's constant, Z = atomic number of the isotopes. Though Pb208, Pb206 and Pb204 have different atomic masses, Z will be same for them i.e 82
=
and
⇒
⇒ λ2 =
Light with an energy flux of 18 W/cm2 falls on a non-reflecting surface at normal incidence. The pressure exerted on the surface is
2 N/m2
2 × 10-4 N/m2
6 N/m2
6 × 10-4 N/m2
The dimensional formula of Planck's constant is
[ M L2 T-1 ]
[ M L2 T-2 ]
[ M L0 T2 ]
[ M L T2 ]
Which out of the following, cannot produce two coherent sources?
Lloyd's mirror
Fresnel biprism
Young's double slit
Prism
In Young's double slit experiment, the two slits act as coherent sources of equal amplitude and of wavelength λ. In another experiment with the same set up, the two slits are sources of equal amplitude and wavelength λ, but are incoherent. The ratio of intensities of light at the midpoint of the screen in the first case to that in the second case is
2 : 1
1 : 2
3 : 4
4 : 3
If the kinetic energy of a particle is increased by 16 times, the percentage change in the de Broglie wavelength of the particle is
25 %
75 %
60 %
50 %
If the half lives of a radioactive element for and β decay are 4 years and 12 years respectively, the ratio of its initial activity and that after 12 years will be
6.25 %
12.5 %
25 %
50 %