It is known that the horizontal component of geomagnetic field magnetic induction intensity in Huaiyin district is 3.0× 10-5T, and a metal rod with a height of 10m is installed at the top of the distr

It is known that the horizontal component of geomagnetic field magnetic induction intensity in Huaiyin district is 3.0× 10-5T, and a metal rod with a height of 10m is installed at the top of the district TV building as a lightning rod. According to ampere force formula F=BIL=3× 10? -5× 105× l0 = 30n。 The horizontal component of geomagnetic field is northward and the discharge current is downward. According to the left-handed rule, it is judged that the direction of magnetic force on the metal bar is from west to east. Therefore, A is correct and BCD is wrong;

So choose a.