NEW!  CBSE Papers PDF: Class-X, Class-XII

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## Maximum Marks:  70 Marks                                                             Time Allowed: 3 hours

General Instructions:
(1) All questions are compulsory. There are 33 questions in all.
(2) This question paper has five sections: Section A, Section B, Section C, Section D and
Section E.
(3) Section A contains ten very short answer questions and four assertion reasoning MCQs of 1 mark each, Section B has two case based  questions of 4 marks each, Section C contains nine short answer questions of 2 marks each, Section D contains five short answer questions of 3 marks each and Section E contains three long answer questions of 5 marks each.
(4)  There is no overall choice. However internal choice is provided. You have to attempt
only one of the choices in such questions.

 Sr. No. Marks Section – A All questions are compulsory. In case of internal choices, attempt any one of them. 1 Name the physical quantity having unit J/T. 1 2 Mention one use of part of electromagnetic spectrum to which a wavelength of 21 cm (emitted by hydrogen in interstellar space) belongs. OR Give the ratio of velocity of the two light waves of wavelengths 4000Å and 8000Å travelling in vacuum. 1 3 An electron with charge -e and mass m travels at a speed v in a plane perpendicular to a magnetic field of magnitude B. The electron follows a circular path of radius R. In a time, t, the electron travels halfway around the circle. What is the amount of work done by the magnetic field? 1
 4 A solenoid with N loops of wire tightly wrapped around an iron-core is carrying an electric current I. If the current through this solenoid is reduced to half, then what change would you expect in inductance L of the solenoid. OR   An alternating current from a source is given by i=10sin314t.  What is the effective value of current and frequency of source? 1 5 What is the value of angular momentum of electron in the second orbit of Bohr’s model of hydrogen atom? 1 6 In a photoelectric experiment, the potential required to stop the ejection of electrons from cathode is 4V. What is the value of maximum kinetic energy of emitted Photoelectrons? 1