16.By tangent law, the field due to the magnet is

17.The reduction factor k of a tangent galvanometer is

18.During the initial adjustment, the magnetic needle of the deflection magnetometer in Tan B position

19.Magnetic intensity due to a bar magnet of length 2l and pole strength ‘m’ at an equatorial point at a distance ‘d’ from the mid-point is

20.A magnetic needle suspended at a place having two magnetic fields comes to rest when