25. Two fixed long parallel horizontal rails, a distance 1 m apart are joined at one end by a resistance 10. A rod AB of negligible resistance slides towards the resistance. A magnetic field of magnitude 4T perpendicular to the plane of rails exists. Find the current flowing (in Ampere) in the resistance, at an instant when the velocity of the rod is 2 m/s. Im 2m/s B B=4T x 26. 27. A radioactive sample decays with a constant of log, 2s'. If initially there are 200 nuclei 1 3 present, find the number of nuclei decayed during the first 9 seconds. In the colour coding system of carbon resistors, the tolerance (in %) shown by gold band is