17. Some energy levels of a molecule are shown in the figure. The ratio of the wavelengths r=/2, is given by -E- -E 241 -2E- -3E- 3 1 (1) r= (2) 3 4 2 (3) (4) 3 18. A man grows into a giant such that his linear dimensions increase by a factor of 9. Assuming that his density remains same, the stress in the leg will change by a factor of 1 (1) 81 (2) 81 (3) 9 (4) 61 19. In a coil of resistance 100 2, a current is induced by changing the magnetic flux through it as shown in the figure. The magnitude of change in flux through the coil is Current (amp.) 0.5 s Time (1) 250 Wb (2) 275 Wh (4) 225 Wh (3) 200 Wh 20. In a Young's double slit experiment, slits are separated by 0.5 mm, and the screen is placed 150 cm away. A beam of light consisting of two wavelengths, 650 nm and 520 nm, is used to obtain interference fringes on the screen. The least distance from the common central maximum to the point where the bright fringes due to both the wavelengths coincide is : (1) 9.75 mm (3) 1.56mm (2) 15.6mm (4) 7.8mm 21. A magnetic needle of magnetic moment 6.7 10-2 Am and moment of inertia 7.5 x 106 kg m2 is performing simple harmonic oscillations in a magnetic field of 0.01 T. Time taken for 10 complete oscillations is: (1) 6.98 s (3) 6.65s (2) 8.76s (4) 8.89 s 22. The variation of acceleration due to gravity g with distance d from centre of the earth is best represented by (R= Earth's radius): (1) (3) (2) OR g g R g (4) d. Activa OR