SCHOLASTIC APTITUDE TEST 1996.

PHYSICS

• Answers must be written either in English or the medium of instruction of the candidate in high school.
• There will be no negative marking.
• There are THREE Sections. Answer all questions of a section at one place.
• Use of calculators or graph papers is not permitted.
• Marks allotted for individual sections are given below. All questions in an individual section carry equal marks.

Section A 10 Marks
Section B 20 Marks
Section C 30 Marks

SECTION A

1. A large amount of ice at 0 ° C is added to a beaker of water at 30 ° C. Some of the ice melts and the rest floats on water in the beaker. The temperature of the water in the beaker is              .                                                               
2. The angle of minimum deviation of an equiangular prism is equal to the angle of the prism. The refractive index of the material of the prism is                 .                                                                                                              
3. A wave of frequency 170 Hz travels through a narrow pipe closed at one end where it is reflected. The reflected wave and the incident wave interfere forming a stationary wave in the pipe. If the nearest antinode in the pipe is 50 cm from the closed end, the velocity of the wave is                         .                
4. For compressions and rarefactions to form in a medium the direction of vibration of the particles and the direction of propagation of the wave must be                            .                                                                                             
5. When a person speaks in to a microphone the vibrations of its diaphragm are  free/ resonant/forced . ( Mention the correct answer in your response sheet )                                                                                   
6. A current of 3.2 mA is flowing through a wire. The number of electrons crossing any section of the conductor in a minute would be                               .                                                                                   
7. A long wire has electronic current flowing through it from north to south. The north pole of a compass needle placed above the wire would deflect towards                               .
8. A filament lamp is rated 100 W at 200 V. The filament is cut in to two equal parts and one of them is used at 250 V. Its power would be                                .                                                                                   
9. A hypothetical radioactive nucleus emits a proton and a deuteron in succession. The mass number and charge number of the product nucleus are reduced by                            and                           respectively.                                                                                                                                                                      
10. When aluminum is bombarded with alpha particles, the resulting nucleus becomes radioactive and emits                                  particles.

11. With x axis westward and y axis southward the coordinates of two places are 150 m, 200 m and 450 m, 600 m.
    The westward distance between the places is                               .
    The southward distance between the places is                               .
    The distance between the places is                               .                                                                                   
12. A solid is heated by a source supplying heat at a constant rate. The temperature at first rises from 20° C to 80° C in 5 minutes and then remains steady for 60 minutes before it starts rising again. The ratio of specific heat of the solid to its latent heat of fusion is                       .                                                                                   
13. A concave mirror is kept some distance away from a wall. A twice magnified image is formed on the wall when an object is placed between the mirror and the wall at a distance of 30 cm from the wall. The focal length of the mirror is                        .                                                                                   
14. In the expression
          v, E and D denote velocity, Elasticity and density. Then a and b are equal to          and           respectively.                                                                                   
15. Charge stored by a condenser is 5 mC when a potential difference of 2 V is maintained between its plates and the plates have a material of dielectric constant 5 between them. Charge on the plates when the potential difference is doubled and the material between the plates is replaced by material of dielectric constant 2 would be                               .                                                                                   
16. A cell drives a certain charge through a circuit in a certain time. Due to a change in the resistance of the circuit in which this cell is a part the same charge takes twice greater time to be driven. Work done in the first and second cases by the cell are in the ratio                               .                                                                                   
17. A charged liquid is flowing through a pipe of cross sectional area a. Unit volume of this liquid has a charge q. If the velocity of the flow is v, current through any section of the pipe is               .                                                                                   
18. Two wires are made of equal mass of same material and have their cross sections in the ratio 3:4. Their resistances will be in the ratio                               .                                                                                   
19. To raise the temperature of 10 liters of water through 20 C° a 1000 W heater would require                                minutes.                                                                                   
20. A length of wire is made in to circular coil with certain number of turns. For a certain current through it the magnetic field at it’s center is X. If another coil made of same length of wire has twice greater number of turns, magnetic field at it’s center for same current as the first coil would be                               .

SECTION C

21. The distance of a particle moving along a straight line from another stationary point on the same line is given by l = 2+ 4t + 5 t² with l in meters and t in seconds. The distance travelled by the body between 4 th and 6 th seconds will be                               .                                                                                   
22. Two cars are travelling on a straight road with the one car 200 m from the other at the same speed. At a certain moment brakes are applied to the rear car and it decelerates uniformly travelling 20 m before coming to rest. The distance between the cars at the moment the rear car comes to rest is                          .                                                                                   
23. Two points A and B are located on the floor of a room 30 cm and 20 cm away from a wall. The distance between the points parallel to the wall is 50 cm. An insect is at A moving on the floor at 5 cms^–1. It has to first reach a point C on the wall and then reach B such that AC and BC make equal angles with normal to the wall at C The time taken for this motion would be                              .                                                                                   
24. Two particles are going round concentric circular paths making 30 RPM and 60 RPM. the time interval between their being at the minimum and maximum distances is                .                                                                                   
25. A wooden block of certain volume is floating in water with a metal block of one eighth its volume hanging from below it. The volume of the submerged portion of the wooden block is one fourth its total volume. When the metal block is placed on top of the wooden block, the volume of the submerged portion of the wooden block is three fourths its total volume. The ratio of densities of wood and metal is                      .                                                                                             
26. Intensity of light at a point is proportional to square of the distance of the point from a source of light. A source of light is at a height of 30 cm above the center of a circular table of radius 40 cm. The ratio of intensities at the center and the edge of the table is               .                                                                                   
27. Two points on a thin circular ring are located such that the radial lines joining them to the center have a certain angle between them. When this angle is 90° the electrical resistance offered by the ring for a current entering one point and leaving the other is R. The resistance when the angle is 60° will be                               .                                                                                   
28. An electron moving vertically upward in a horizontal magnetic field experiences a force directed towards east. The force experienced by an electron travelling eastward in this magnetic field will be directed towards                           .                                                                                   
29. Radii of circular paths of electrons round the nuclei are proportional to the square of quantum numbers. If square of time taken to go round circular path once by an electron is proportional to cubes of the radius, The ratio of frequencies of revolution in orbits of quantum numbers 1 and 4 is                             .                                                                                   
30. Mass of a radioactive substance at a certain moment is 16 gm and its half life is 2 hrs. The mass of the substance that disintegrates in 1 hour is  greater than / equal to / less than  4 gm. ( Mention the correct answer in your response sheet and justify your answer)