21. Three resistances of magnitude R each are connected in the form of an equilateral triangular loop of side a. The combination is placed in a magnetic field B = Boe perpendicular to its plane. The induced current in the circuit is given by t Boe- x3R a. The value of x is (Neglect self inductance of the loop) X X X X X X XXXXXX X X X X *XXX XXX: x x X X R X X A XXX XXX X X X X X X X XXXR XXXX X X X X XXXX X X X X X X X X X X xxxx xxxxxx x XXXXXX * *B www X X X X X X X RX X XXXX Cx x x X X 22. The focal lengths of objective and eye-piece of a compound microscope are 2 cm and 4 cm with a separation of 8 cm. At what distance should the object be placed from the eye-piece such that the strain on eye is minimum (in cm). 23.A neutron having kinetic energy 'k' collides with a stationary hydrogen atom in ground state. If the collision is completely inelastic and hydrogen gets ionized in the process, the kinetic energy of neutron after collision is 'n' eV. Find n. (Assume mass of neutron, hydrogen atom and ionized hydrogen to be the same, ionization energy of hydrogen atom = 13.6 eV)