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Saturday 23rd March 2019
 ICSE Guess > ICSE Papers > Important Questions > Class X > Physics > Physics By M. P. Keshari ICSE Physics Class X Important Papers By M. P. Keshari Q. 1. Name the principle on which functioning of a transformer depends. Q. 2. What is the function of a step-up transformer ? Q. 3. Can a transformer work when it is connected to a d. c. source ? Q. 4. Diagram given below, shows schematically part of a step-down transformer. Draw the complete diagram in your answer sheet. Q. 5. Diagram below shows a circuit containing a coil wound on a long and thin hollow cardboard tube. Copy the diagram. Show the polarity acquired by each face of the solenoid. Draw the magnetic lines of force inside the coil and also show their directions. (iii) Mention two methods to increase the strength of the magnetic field inside the coil.. Q. 6(i) Draw a neat labelled diagram of an a. c. generator. (ii) What is the magnitude of the e. m. f. induced in the coil when its plane becomes parallel to the magnetic field ? Q. 7. The following diagram two straight wires carrying current. Copy the diagram and draw the pattern of lines of force around them and mark their directions.Fig... Q. 8. State two ways of increasing the speed of rotation of a d. c. motor. Q. 9(i) Draw a labelled diagram of the device you would use to transform 200 volts a. c. to 15 volts a. c. (ii) What is the name of this device ? Q. 10. What is an electromagnet ? State two ways by which the strength of an electromagnet can be increased. Q. 11. State two characteristics of a primary coil of a step-up transformer when compared to the secondary coil. Q. 12. With reference to a d. c. motor state: The energy change that takes place The principle on which it operates. Q. 13. Draw a representative diagram of a DC motor. Label the following in your diagram. The field magnet The armature Commutators Wire brushes What is the energy change involved in this case ? Q. 14. State two dissimilarities between a D.C. motor and an A.C. generator. Q. 15. State two advantages of an electromagnet over a bar magnet. Q. 16. Draw a sketch of an electric bell with electrical connections and label the main parts. Why the armature is made of soft iron and not steel? Q.17. The diagram shows a coil connected to a centre zero galvanometer G. The galvanometer shows a deflection to the right when the N-pole of a powerful magnet is moved to the right as shown:   Explain why the deflection occurs in the galvanometer ? Does the direction of the current in the coil appear clockwise or anticlockwise when viewed from the end A ? State the observation in G when the coil is moved away from N. State the observation in G when, both the coil and the magnet, are moved to the right at the same speed. Q.18(a) Draw a labelled diagram to show the various Components of a step-down transformer. (b) State the main difference between a step-up and step-down transformer. Q. 19. Explain briefly how a magnet can be demagnetized using an alternating current. Q. 20. State two ways by which the emf in an A.C. generator can be increased. Q. 21. Name any two electromagnetic waves which have a frequency higher than that of violet light. State one use of each. Q .22. State the energy change which takes place when a magnet is moved inside a coil having a galvanometer at its ends. Name this phenomenon. Q. 23. Draw a labelled diagram of an A.C. generator. Q .24. State the function of a split ring in a d. c. motor. Q. 2 . Mention two reasons why a soft iron core is used within the coil of a moving coil galvanometer. Q. 26. State two advantages of an electromagnet over a permanent magnet. Q. 27. What will happen to a compass needle when the compass is placed below a wire and a current is made to flow through the wire ? Give a reason to justify your answer. Q. 28. What energy conversion takes place during the working of a d. c. motor ?

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