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PHYSICS SA II Q.1.) Displacement distance graph of two sounds A and B are as given below and travelling in a medium 80 MARKS (2) Study the two types of sound waves and compare their : a.) Amplitude b.) Wavelengths Q.2.) a.) What do you understand by the term nuclear fusion? (2) b.) Nuclear power plants use nuclear fission reaction to produce electricity. What is the advantage of producing electricity by fusion reaction? Q.3.) a. What do you understand by free vibrations of a body? b. Why does the amplitude of a vibrating body continuously decrease during damped vibrations? (2) Q.4.) a. How is the c.m.f. across primary and secondary coils of a transformer related with the number of turns of coil in them ? (2) b. On which type of current do transformers work? Q.5.) a. What are isobars ? Give one example of isobars. (2) Q.6.) State any two advantages of electromagnets over permanent magnets. (2) Q.7.) The The diagram shows a coil wound around a U shape soft iron bar AB. (a) What is the polarity induced at the ends A and B when the switch is pressed ? (b) Suggest one way to strengthen the magnetic field in the electromagnet. (c) What will be the polarities at A& B if the direction of current is reversed in the circuit ? (3) Q.8.) The ore of Uranium found in nature contains92 U218 and 92U235. Although both the isotopes are fissionable, it is found out experimentally that one of the two isotopes is more easily fissionable. (3) a. Name the isotope of Uranium which is easily fissionable. b. Give a reason for your answer. c. Write a nuclear reaction when Uranium 238 emits an alpha particle to form a Thorium (Th) nucleus. Q.9.) Radiations given out from a source when subjected to an electric field in a direction perpendicular to their path (4) are shown below in the diagram. The arrows show the path of the radiation A, B and C. Answer the following questions in terms of A, B and C. (i) Name the radiation B which is unaffected by the electrostatic field. (ii) Why does the radiation C detlect more than A ? (iii) Which among the three causes the least biological damage externally? (iv) Name the radiation which is used in carbon dating. Q.10.) Arrange the Q.11.) An , infra-red rays , ultra-voilet rays and X rays in their increasing order of frequencies (2) particle absorbs an electron . What does it change to ? (2) Q.12.) How will you demagnetize an electromagnet? (2) Q.13.) What adjustment will you make for turning a stringed instrument such as a violin to emit a desired pitch? (2) Q.14.) Explain the working principle of a d.c. motor with a proper neat labeled diagram . (4) Q.15.) a (4) b (2) Q.16.) A bat emits an ultrasonic sound of frequency 0.25 MHz . Calculate the time in which one vibration is completed. Q.17.) The wave-length of red colour is 7 10 m and that of blue colour is 4 10 m. What will be the speed of the colours in vaccum and glass. (2) Q.18.) Write two main advantages of the ring main system of power distribution. Also explain the working of the ring main system of power distribution . (3) Q.19.) What is the use of a fuse in household circuit ? Also explain how a switch can be operated in a lobby having two ends A and B such that the lobby lights can be operated from both ends. (4) Q.20.) a.) If a monochromatic beam of light , undergoes minimum deviation through a prism , how does the beam pass through the prism , with respect to its base. b. If the white light is used in the same way as mentioned above in (a) , what change is expected in the emergent beam. Q.21.) (4) (2) (4) (4) Q.22.) (4) Q.23.) An electric bulb is rated at 100 W , 250 W . How much current will the bulb draw if connected to a 250 V supply. Q.24.) What do you mean by power rating of an electrical appliance? How do you use it to calculate (a) The resistance of the appliance. (b) The safe limit of current in it , while it is in use (1) Q.25.) Name and state the rule by which polarity at the ends of a current carrying solenoid is determined and how (2) Q.26.) Distinguish between electromagnet and permanent magnet (2) Q.27.) a.) Describe briefly one way of producing an induced emf. (4) (2) b. ) State one factor that determines the magnitude of induced emf . c.) What factor determines the direction of induced emf d.) Mention any one example where induced emf is used practically. Q.28.) Distinguish between Step Up Transformer and Step Down Transformer . Also derive the equations for the turns ratio. (3)
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