(Code-I015/12P2) NRT INDIA QUESTION PAPER CLASS-XII (Code-I015/12P2) Time : 3 Hrs Topic : Electrostatic Student’s Name:…………………. Max. Marks : 70 Date : …………………….. SID NO:……….…... GENERAL INSTRUCTIONS: 1. Answer to this Paper must be written on the Answer Copy. 2. You will not be allowed to write during the first 05 minute. This time is to be spent in reading the Question Paper. 3. The time given at the head of this paper is the time allowed for writing the answer. 12. Name the physical quantity which has its unit Section –A (1 Mark each) (Attempt all questions) joule coulomb−1. Is it a scalar or vector? 13. What is the potential due to a point charge? 1. Distinguish between a dielectric and a 14. The safest way to protect yourself from lighting conductor? is to be inside a car. Comment. 2. What is electric charge? 3. Can a body has charge 1.5 e, where e is the 15. What is a net charge on a charge capacitor? 16. What is the order of capacitances used in electronic charge? power supplies? 4. A body has excess of electrons what does it imply? Section –B (2 Mark each) (Attempt all questions) 5. What is the value of charge on electron? Is a charge less than this value possible? 6. Electric charge is additive in nature, explain? 7. What is the basic cause of quantization of 9. weather. Explain, why? 18. Can a charged body attract another uncharged charge? 8. 17. Automobile ignition failure occurs in damp Quarks are the building blocks of nucleons and body? Explain. possess fractional electronic charge. Dos this 19. Can ever the whole excess charge of a body be discover violate the principle of quantization of transferred to the other? If yes, how and if not charge? why? What do electric lines of force represent? 10. Why two electric lines of force cannot intersect 20. How many electrons must be removed from a ball of mass 3.2 g so that it may float in an electric field of intensity 1010 N/C directed each other? 11. Why there is no work done in moving a charge from one point to another on an equipotential upwards? 21. Define relative permittivity of a medium. surface? NRT India , 14/32, RLB Road Near Munshi Pulia, Indira Nagar, Lucknow. Call: 0522-2714802, 9415905513, 8090510938 Branches : Indira Nagar, Gomti Nagar, Hazratganj 1 (Code-I015/12P2) NRT INDIA 22. Two points charges +Q and +4Q are separated by a distance of 6a. Find the point on the line Section –C (3 Mark each) (Attempt all questions) joining the two charges where the electric field 31. The opposite corners of a square charge each and the other two opposite corners is zero? 23. The electric potential at 0.1 m from a point charge is +50V. What is the magnitude and three equipotential surfaces corresponding to a field that uniformly increases in magnitude of the same square carry q charge each. If the resultant force on q is zero, how are Q and q related? sign of the charge? 24. Draw carry Q but remains constant along Z- 32. A spherical conductor of radius 12 cm has a charge of 1.6 ×10−7C distributed uniformly on its surface. What is the electric field. direction. How are these surfaces different from (i) Inside the sphere? that of a constant electric field along z-direction? (ii) Just outside the sphere? 25. The kinetic energy of a charged particle (iii) at a point 18 cm from the centre of the sphere? decreases by 10J as it moves from a point at potential 100 V to a point at potential 400 V. Find the charge on the particle. Section –D (15Mark each) (Attempt any four questions) 26. Work done in moving a test charge between two points in an electric field is independent of the path followed. Comment. 27. How does an electrically polarized object differ from an electrically charged object? each. They coalesce to form a bigger drop. Calculate the potential of bigger drop. 29. A number of spherical conductors of different radii have same potential. How does the surface charge density on them relate to radius? 30. A small particle carrying a negative charge 1.6 ×10 C is suspended in and qD=−5μC are located at the corners of a square ABCD of side 10 cm. What is the force on a charge of 1μC placed at the centre of the 28. 27 drops of same size are charged at 220 V −19 33. Four point charges qA=2μC, qB=−5μC, qC=2μC equilibrium between the horizontal metal plates 5 cm apart, square? 34. Given figure shows a charge array known as an electric quadrupole. For a point on the axis of the quadrupole, obtain the dependence of potential on r for r/a>>1 and contrast your results with that due to an electric dipole and an electric monopole (i.e., a single charge) A q a B −q –q having potential difference of 3000 V across a C q q r them, find the mass of the particle. NRT India , 14/32, RLB Road Near Munshi Pulia, Indira Nagar, Lucknow. Call: 0522-2714802, 9415905513, 8090510938 Branches : Indira Nagar, Gomti Nagar, Hazratganj 2 (Code-I015/12P2) NRT INDIA 35. Geeta has dry hair. A comb ran through her dry 37. hair attract small bits of paper. She observes that Neeta with oily hair combs her hair; the comb could not attract small bits of paper. She consults her teacher for this and gets the answer. She then goes and shows this to the junior classes phenomenon as physics experiment to them. All the juniors feel very happy and tell her that they will also took for such interesting things in nature and try to find the answer. She succeeds in forming a science club in her school. Read the above passage and answer the following question. (i) 38. In Pradeep’s classroom the fan was running very slowly. Due to which his teacher was sweating and was restless and tired. All his classmates wanted to rectify this. They called an electrician who came and change the capacitor only after which the fan started running fast. (i) What energy is stored in the capacitor and where? (ii) What values did the classmate have? A man travelling in a car during heavy rain and thunderstorm sees a boy standing under a tree. He immediately stops his car and asks the boy to get inside the car and saves him from a possible natural calamity. Answer the following questions based on the above information. (i) What danger did the boy had while standing under the tree during the thunderstorm? (ii) How is it safer inside the car during such weather? (iii) What according to you are the values displayed by the man to help the boy? (iv) Give another example from everyday life situation which represent display of similar values. What according to you are the values displayed Geeta? (ii) Explain the phenomenon involved. 36. Four points charges +1μC, +1μC, −1μC and −1μC are placed at the corners A, B, C, D of a square of each side 0.1 m. (i) Calculate electric potential at the centre 0 of the square. (ii) If E is middle point of BC, what is the work done in carrying an electron from 0 to E? Signature of Guardian Examination Superintendent (Seal & Signature) NRT India , 14/32, RLB Road Near Munshi Pulia, Indira Nagar, Lucknow. Call: 0522-2714802, 9415905513, 8090510938 Branches : Indira Nagar, Gomti Nagar, Hazratganj 3