Short Answer Typei) State Brewster's law of polarization of light.
ii) How will you identify with the help of experiment whether a given beam of light is of polarized light or unpolarized light.
i) Brewster's law states that when ordinary or unpolarized light is incident on a transparent medium, the reflected light is completely plane polarised for a certain angle of incidence 
.
where 
is the polarising angle,
n is the refractive index of the transparent medium.
ii) When an incident light is allowed to fall on a polarizer, which is then rotated, if the intensity of the transmitted light varies, the light is polarised light. If the transmitted light does not vary in intensity or remains constant, the light is unpolarized light.
A narrow beam of monochromatic light, PQ, is incident normally on one face of an equi-angular glass prism of refractive index 1.45. When the prism is immersed in a certain liquid, the ray makes a grazing emergence along the other face as shown in the figure below. Find the refractive index of this liquid.
When two thin lenses of focal length f1 and f2 are kept coaxially and in contact, prove that their combined focal length 'f' is given by:
The figure below shows the positions of a point object O, two lenses, a plane mirror and the final image I which coincides with the object. The focal length of the convex lens is 20 cm. Calculate the length of the concave lens.
i) Define magnifying power of a microscope in terms of visual angles.
ii) What is the advantage of a compound microscope over a simple microscope?
An astronomical telescope uses two lenses of power 10 dioptre and 1 diopter. If the final image of a distant object is formed at infinity, calculate the length of the telescope.
Answer the following questions with reference to Milikan's oil drop experiment:
i) What is an atomiser?
ii) What is the use of an x-ray tube?
iii) What is the unique property shown by the charge of an oil drop?
i) Write Einstein's photoelectric equation.
ii) If the frequency of the incident radiation is increased from 4 x 1015 Hz to 8 x 1015 Hz, by how much will the stopping potential for a given photosensitive surface go up?
i) What are matter waves?
ii) Show with the help of a labelled graph how their wavelength (
) varies with their linear momentum?
The energy levels of an atom of a certain element are shown in the figure below. Which one of the transitions A,B,C,D or E will result in the emission of photons of electromagnetic radiation of wavelength 618.75 nm? Support your answer with mathematical calculations.
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