CBSE Guess > Papers > Important Questions > Class X > 2009 > Science > Science By Mr. siddhartha Dixit CBSE CLASS X Q. 1. Why is Tungsten metal selected for making filaments of incandescent lamp bulbs? Q. 2. A torch bulb is rated at 3V and 600mA. Calculate it’s a) Power b) Resistance c) Energy consumed if it is lighted for 4 Hrs. Q. 3. Why pure iron is not used in making permanent magnets. Name materials used for making permanent magnets. Describe how permanent magnets are made electrically? State two examples of electrical appliances which use permanent magnets. Q. 4. Which will offer more resistance a 50W lamp or 25W lamp bulb and how many times? Q. 5. What are magnetic field lines? How is the direction of a magnetic field lines at a point determined? Q. 6. Draw two field lines around a bar magnet along its length on its two sides and mark the field direction on these by arrows. Q. 7. List any three properties of Magnetic lines of force. Q. 8. Should the heating element of an electric iron be made of iron, silver or nichrome wire? Why. Q. 9. A steady current is passed for 30minutes through two voltmeters connected in series: a copper voltmeter [Cu cathode in copper sulphate solution], and a silver voltmeter [Ag cathode in silver nitrate solution]. If the mass of copper deposited in the first voltameter is 21.17g, Calculate the mass of silver deposited on the cathode in the other voltameter. Given relative atomic mass of Cu = 63.5 and Ag = 108. Q. 10. State Fleming’s left hand rule. With a labeled diagram, describe the working of an electric motor. What is the function of a Split ring commutator in a motor? Q. 11. Find the net power consumed by the two resistors R1 and R2 connected in series to a source of V volts. Q. 12. What is the principle behind the working of an A/C generator? How can we find the direction of the current in the armature of the generator? Q. 13. If a wire is stretched to triple its original length, what happens to its resistivity? Q. 14. In the given fig. current carrying conductor is placed above and below the magnetic needle. Predict the deflection in the needle in each case. Q. 15. In a resistance R1 a current of 1A is passed. What is the amount of electrical energy dissipated in 1second? Q. 16. Define Electrolysis. State Faraday’s laws of electrolysis. Define resistivity of any material. Q. 17. State the rule to find the direction of magnetic field produced around a current carrying conductor. State the characteristics of magnetic force. Q. 18. Give differences between magnetic and electric force. Q. 19. Two identical resistors each of resistance 10 ohm are connected 1) in series 2) in parallel, in line to a battery of 6volts. Calculate the ratio of power consumed in the combination of resistors in the two cases. Q. 20. What are the factors on which the strength of magnetic field produced by a current carrying solenoid depends? Q. 21. A bulb is rated at 220V- 100W. What is its resistance? Five such bulbs burn for 4 hrs. What is the energy consumed? Calculate the cost if the rate is 50paise per unit? Q. 22. Express ohm’s law mathematically. Draw a circuit diagram to verify Ohm’s law. Present the relationship between the voltage applied across a conductor and the current flowing through it graphically. Q. 23. State Right hand thumb rule for finding the direction of magnetic field, around a current carrying straight conductor. How will the magnetic field be affected :
Q. 24. What type of energy transformations take place in electric motor? Name two devices which use electric motor as necessary component? Q. 25. Two lamps rated 100W, 220V and 25W, 220V are connected in parallel to 220V supply. Calculate the total current through the circuit. Q. 26. A metallic coil connected to a 220V supply has a resistance of 110 ohm. How long will it take this coil to heat 1kg water from 2o0C to 700C? Assume whole heat produced by coil is taken up by water. (Specific heat capacity of water = 4186 ) Q. 27. Why is much less heat generated in long electric than in filaments of electric bulb? Q. 28. In the electroplating process, why is the object to be electroplated is taken as cathode? Q. 29. Should the heating element of an electric iron be made up of iron, silver or nichrome wire? Q. 30. For longer operational life why dry cells should be used intermittently? Q. 31. What is electroplating? Explain the process with a diagram. Give two real life applications of the process. Q. 32. What is superconductivity? Why is the research in superconductivity very important? Q. 33. How does the resistance of wire change when 1) Its length is doubled 2) Area is doubled? Q. 34. Calculate the effective resistance between a) B & C b) A & C. Q. 35. An electric kettle rated 1000W, 220V is used to bring water at 20 degrees to its boiling point. If the kettle is switched on for 10 minutes. Calculate:
Q. 36. Write two advantages and disadvantages of using dry cells. Q. 37. A copper wire has a diameter of 0.5mm and resistivity of . How much of this wire is required to make a 10 ohm coil? Q. 38. A wire of resistance 5ohm is bent in the form of a closed circle. What is the effective resistance between the two points at the end of any diameter of the circle? Q. 39. If a 24V battery is connected to the arrangement of resistance given below, calculate the total effective resistance and the total current flowing in the circuit. Q. 40. State Fleming’s Left and right hand rules. With a labeled diagram describe the working of an electric motor. What is the function of commutator rings in a motor? Q. 41. What is the effect on resistivity of a pure metal with the increase in temperature? Q. 42. What is a fuse? How does it function? Explain the terms: Short Circuiting, Overloading and Van Allen belts. Q. 43. How are ammeter and voltmeter connected in circuit? What are the ideal resistances for these components? Q. 44. Define one faraday/ tesla. Paper By Mr. siddhartha Dixit
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