The distance between the first and the sixth bright fringes formed in Young’s double slit experiment (measured by a spectrometer) is found to be 12.5 mm. The separation between the slits is 0.12 mm and the distance of the screen from the slits is 60 cm. Calculate :
(i) the fringe width
(ii) the wavelength of the light used (in nm).
(i) What is the difference between the electric field vector E at any point in the path of a linearly polarized light and that of an un-polarized light ?
(ii) Briefly describe how a given beam of light can be analysed and determined if it is linearly polarized or un-polarized.
A plano-convex lens made of glass (n = 1 5) has a focal length 10.0 cm.
(i) Calculate the radius of curvature of its curved surface.
(ii) If an identical plano-convex lens is placed in contact with the first (plane surfaces facing each other), what will be the power of the combination (in dioptres) ?
(i) State the three conditions for the formation of a pure spectrum.
(ii) Draw the ray diagram illustrating the measurement of the angle of a prism using a spectrometer.
The work function for sodium is 2.28 eV. [3]
(i) What is the minimum energy for a quantum of radiation to cause photoelectric emission from a sodium surface ?
(ii) Calculate the wavelength of this radiation.
Mass defect : The difference between the sum of the mass of the nucleons constituting a nucleus and the rest mass of the nucleus is known as mass defect.
It is denoted by m.
Δm = sum of mass of nucleons - mass of nucleus.
Given,
Mass No. of heavy nucleus is A = 240 , and
binding energy/nucleon = 7.5 MeV
Therefore,
Total binding energy of nucleus = 240 x 7.6 Mev
= 1824 MeV
It splits into two nuclei of Mass No. A1 = 120.
Therefore,
Binding energy per nucleon = 8.5 MeV
∴ Total binding energy of two nuclei = 2 x 120 x 8.5 MeV
= 2040 MeV.
∴ Disintegration energy Q = 2040 - 1824 MeV
Q = 216 MeV