1. 24. Students I, II and III perform an experiment for measuring the acceleration due to gravity (g) using a simple pendulum. They use different lengths of the pendulum and/or record time for different number of oscillations. The observations are shown in the table. Least count for length = 0.1 cm Least count for time = 0.1 s Student Length of the pendulum (cm) Number of oscillations (n) Total time for (n) oscillations(s) Time period(s) I 64.0 8 128.0 16.0 II 64.0 4 64.0 16.0 III 20.0 4 36.0 9.0 If EI, EII and EIII are the percentage errors in g, i.e. ( Δg g × 100 ) for students, I, II, and III respectively,   EI = 0   EI is minimum   EI = EII   EII is maximum   Hint Half-n-half Clue   2. 25. Figure shows three resistor configurations R1, R2 and R3 connected to 3 V battery. If the power dissipated by the configuration R1, R2 and R3 is P1, P2 and P3, respectively, then Figure :   P1 > P2 > P3   P1 > P3 > P2   P2 > P1 > P3   P3 > P2 > P1   Half-n-half Clue   3. 26. Which one of following statements is WRONG in the context of X-rays generated from a X-ray tube?   Wavelength of characteristic X-rays decreases when the atomic number of the target increases   Cut-off wavelength of the continuous X-rays depends on the atomic number of the target   Intensity of the characteristic X-rays depends on the electrical power given to the X-ray tube   Cut-off wavelength of the continuous X-rays depends on the energy of the electrons in the X-ray tube   Half-n-half Clue   4. 27. Two beams of red and violet colours are made to pass separately through a prism (angle of the prism is 60º). In the position of minimum deviation, the angle of refraction will be   greater for the red colour   greater for the violet colour   equal but not 30º for both the colours   30º for both the colours   Half-n-half Clue   5. 28. An ideal gas is expanding such that PT2 = constant. The coefficient of volume expansion of the gas is   1 T   2 T   3 T   4 T   Half-n-half Clue   6. 29. A spherically symmetric gravitational system of particles has a mass density ρ = { ρ0 for r ≤ R 0 for r > R where ρ0 is a constant. A test mass can undergo circular motion under the influence of the gravitational field of particles. Its speed V as a function of distance r (0 < r < ∞) from the centre of the system is represented by   Half-n-half Clue   7. 30. Two balls, having linear momenta p1→= p i^ and p2→= − p i^ , undergo a collision in free space. There is no external force acting on the balls. Let p'1→and p'2→be their final momenta. The following option(s) is (are) NOT ALLOWED for any non-zero value of p, a1, a2, b1, b2, c1 and c2 .   p'1→= c1k^ p'2→= c2k^   p'1→= a1 i^ + b1j^ + c1k^ p'2→= a2 i^ + b2j^ − c1k^   p'1→= a1 i^ + b1 j^ + c1 k^ p'2→= a2 i^ + b2 j^ -;020;- p'1→= a1 i^ + b1j^ p'2→= a2 i^ + b1j^   Half-n-half Clue