9th Standard Annual Exam - Answer Key

1. Galvanometer       (1)
2. 0                            (1)
3. Fig 3                      (1)
4. 0, It is attracted by all parts (2)
5.a. cde (1)
   b. Law of conservation of momentum (1)
6. aFig 2    (1)
    b. Fig 3     (1)
7.a. Intensity increases (1)
   b. Effective resistance decreases so current increases.(1)
8. a. Electrical Energy to Mechanical Energy   (1)
    b. Electrical Energy to Heat Energy               (1)
9. Draw the figure (2)
10.  The mass at the bottom increases. So the Centre of gravity lowered. It  will        become more stable       (2)
 11.a. Ammeter reading decreases (1)
      b. Temperature decreases Resistance decreases. so current increases ammeter reading increases(2)
12. a. Myopia   (1)
b. Eye sphere is large
 Power of the lens is more (2)
c. Using concave lens of suitable focal length (1)

13.a. The current carrying conducter experience a magnetic field around it.(2)
     b. It deflects more (1)
     c. Change the direction of the current(1)

14 a. Voltmeter and ammeter connections are changed. Add a switch in the circuit (2)
   b. rheostat to vary the current by varying resistance. Ammeter to know the current and voltmeter to measure the voltage. (2)
15. a. Fig 4. It is thick soft iron core. (2)
      b. Electrci bell, Electromagnetic relay,   (2)

16. a 100 (1)
      b. I = V/R 20/100 = .2 A  (2)
      c.decreases   (1)

16B a. 1/R = 1/4 + 1/6 +1/12 = 6/12
           R = 12/6 = 2 ohm     (2)
      b. I = V/R = 8/4 = 2 A (2)