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# Question Paper (Section wise)

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Question 1
Positive Marks: 4 / Negative Marks: 1
•  1) Surface of certain metal is first illuminated with light of wavelength λ1 = 350 nm and then, the light of wavelength λ2 = 540 nm. It is found that the maximum speed of the photo electrons in the two cases differ by a factor of 2. The work function of the metal (in eV) is close to: 1. 1.8

2. 2.5

3. 5.6

4. 1.4

•  2) A sample of radioactive material A, that has an activity of 10mCi (1 Ci = 3.7 × 1010 decays/s), has twice the number of nuclei as another sample of different radioactive material B which has an activity of 20mCi. The correct choice for half-lives of A and B would then be respectively:
1. 5 days and 10 days

2. 10 days 40 days

3. 20 days 5 days

4. 20 days 10 days

•  3) Three blocks A, B and C are lying in a smooth horizontal surface, as shown in the figure. A and B have equal masses, m while C has mass M. Block A is given an initial speed v towards B due to which it collides with B perfectly inelastically. The combined mass collides with C, also perfectly inelastically. The combined mass collides with C, also perfectly inelastically if th of the initial kinetic energy is lost in whole process. What is value of M/m? 1. 5

2. 2

3. 4

4. 3

•  4) A metal plate of area 1 × 10-4 m2 is illuminated by a radiation of intensity 16 mW/m2. The work function of the metal is 5 eV. The energy of the incident photons is 10 eV and only 10 % of it produces photo electrons. The number of emitted photo electrons per second and their maximum energy, respectively, will be: [1eV = 1.6 ×1019J]
1. 1014 and 10 eV

2. 1012 and 5 eV

3. 1011 and 5 eV

4. 1010 and 5 eV

•  5) The modulation frequency of an AM radio station is 250 kHz, which is 10% of the carrier wave. If another AM station approaches you for license what broadcast frequency will you allot?
1. 2750kHz

2. 2900kHz

3. 2250 kHz

4. 2000kHz

•  6) Two force P and Q, of magnitude 2F and 3F, respectively, are at an angle θ with each other. If the force Q is doubled, then resultant also doubled. Then, the angle θ is:
1. 120°

2. 60°

3. 90°

4. 30°

•  7) In a Young’s double slit experiment, the path difference, at a certain point on the screen, between two interfering waves is 1/8th of wavelength. The ratio of the intensity at this point to that at the Centre of a bright fringe is close to:
1. 0.74

2. 0.85

3. 0.94

4. 0.80

•  8) A slab is subjected to the two forces and of same magnitude F as shown in the figure. Force is in XY –plane while force F1 acts along Z- axis at the point . The moment of these forces about point O will be:
1. 2. 3. 4. •  9) In a Wheatstone bridge (see figure) Resistance P and Q are approximately equal. When R = 400 Ω, the bridge is balanced. On interchanging P and Q, the value of R, for balance is 405 Ω. The value of X is close to:
1. 401.5 ohm

2. 404.5 ohm

3. 403.5 ohm

4. 402.5 ohm

•  10) In the above circuit,. Current in L-R1 path is I1 and C- R2 path is I2. The voltage of A. C. source is given by, volts. The phase difference between I1 and I2 is: 1. 60°

2. 30°

3. 90°

4. 150°

•  11) A galvanometer, whose resistance is 50 ohm, has 25 divisions in it. When a current of 4 × 10-4 A passes through it, its needle (pointer) deflects by one division. To use this galvanometer as a voltmeter of range 2.5 V, it should be connected to a resistance of:
1. 250 ohm

2. 200 ohm

3. 6200 ohm

4. 6250 ohm

•  12) The charge on a capacitor plate in a circuit, as a function of time, is shown in the figure: What is the value of current at t = 4 s?
1. Zero

2. 3 µA

3. 2 µA

4. 1.5 µA

•  13) Young’s moduli of two wires A and B are in the ration 7:4 Wire A is 2 m long and has radius R. Wire A is 2 m long and has radius r. Wire B is 1.5 m long and has radius 2 mm. If the two wires stretch by the same length for a given load, then the value of R is closed to:
1. 1.3 mm

2. 1.5 mm

3. 1.7 mm

4. 1.9 mm

•  14) A body of mass m1 moving with an unknown velocity of undergoes a collinear collision with a body of mass m2 moving with a velocity After collision m1 and m2 move with velocities of and respectively.
1. 2. 3. V4 – V2

4. V4 + V2

•  15) A rocket has to be launched from each in such a way that it never returns. If E is the minimum energy delivered by the rocket launcher, what should be the minimum energy that the launcher should have if the same rocket is to be launched form the surface of the moon? Assume that the density of the earth and the moon are equal and that the earth’s volume is 64 times the volume of the moon.
1. 2. 3. 4. •  16) The total number of turns and cross-section area in solenoid is fixed. However, its length L is varied by adjusting the separation between windings. The inductance of solenoid will be proportional to:
1. 1/L

2. L

3. 1/L2

4. L2

•  17) Determine the charge on the capacitor in the following circuit: 1. 200μC

2. 60μC

3. 10μC

4. 2μC

•  18) A rigid square loop of side ‘a’ and carrying current I2 is laying on a horizontal surface near a long current I1 wire in the same plane as shown in figure. The net force on the loop due to the wire will be: 1. Repulsive and equal to 2. Attractive and equal to 3. Zero

4. Repulsive and equal to •  19) The elastic limit of brass is 379 MPa. What should be the minimum diameter of a brass rod if it is to support a 400 N load without exceeding its elastic limit?
1. 1.00 mm

2. 1.16 mm

3. 0.90 mm

4. 1.36 mm

•  20) Water from a tap emerges vertically downwards with an initial speed of 1.0 ms-1. The cross-sectional area of the tap is 10-4m2. Assume that the pressure is constant throughout the stream of water and that flow is streamlined. The cross-sectional area of the stream, 0.15 m below the tap would be: (Take, g = 110 ms-2)
1. 5 × 10-4 m2

2. 5 × 10-5 m2

3. 1 × 10-5 m2

4. 2 × 10-5 m2

•  21) A cubical block of side 0.5 m floats on water with 30% of its volume under water. What is the maximum weight (kg) that can be put on the block without fully submerging it under water? [Take density of water = 103 kg/m3]
•  22) The stopping potential V0 (in volt) as a function of frequency (ν) for a sodium emitter, is shown in the figure. The approximate work function of sodium, from the data plotted in the figure, will be _______ eV. (Given: Planck’s constant (h) = 6.63 × 10-34 Js, electron charge e = 1.6 × 10-19 C) •  23) A submarine (A) travelling at 18 km/hr is being chased along the line of its velocity by another submarine (B) travelling at 27 km/hr. B sends a sonar signal of 500 Hz to detect A and receives a reflected sound of frequency ν. The value of v is close to ________ Hz. (Speed of sound in water = 1500 ms-1)
•  24) The reading of the ammeter (in mA) for a silicon diode in the given circuit is •  25) A convex lens (of focal length 20 cm) and a concave mirror, having their principal axes along the same lines, are kept 80 cm apart from each other. The concave mirror is to the right of the convex lens. When an object is kept at a distance of 30 cm to the left of the convex lens, its image remains at same position even if the concave mirror, by itself would produce a virtual image would be _______ cm.
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