Find the magnitude of the magnetic flux through the floor of a house that measures 21 m by 18 m . assume that the earth's magnetic field at the location of the house has a horizontal component of 2.8

Find the magnitude of the magnetic flux through the floor of a house that measures 21 m by 18 m . assume that the earth's magnetic field at the location of the house has a horizontal component of 2.8×10−5 t pointing north, and a downward vertical component of 4.8×10−5 t .