(i) What is a continuous emission spectrum? Name one source of light which produces such a spectrum.
(ii) Explain in brief why dark lines are observed in the solar spectrum.
(i) What are coherent sources?
(ii) In young’s double slit experiment, what is the path differences between the two light waves forming 5th bright band (fringe) on the screen?
(i) In case of polarized light, what is means by the plane of polarization?
(ii) Find refractive index of glass if its polarising angle is 60°.
(i)Explain the statement: “Angular magnification of a compound microscope in normal use is 30”.
(ii) State how the resolving power of an astronomical telescope can be increased.
(i) Angular magnification of a compound microscope in normal use is 30 means that it can magnify the size of the object 30 times.
(ii) By using the Object lens of large aperture in astronomical telescope larger the aperture of the objective lens, smaller the limit of resolution, or greater the resolving power of the telescope.
In Millikan’s oil drop experiment, the two plates are 2 cm apart. When a potential differences of 2355 V is applied between them, an oil drop of radius 1μm is found to remain suspended. Calculate the number of excess electrons on the drop,
[Density of oil = 900 kg/m 3 = Density of air may be ignored]