Answer:
Because they want attention
If you comb your hair and the comb becomes positively charged, then your hair becomes negatively charged.
On or near the surface of the Earth, 1 newton is the weight of about 102 grams of mass.
Note that the gravitational force between the object and the Earth is always the
same. It doesn't matter whether the object is falling, flying, floating, fluttering,
rising, sinking, rolling, sliding, or just laying there. It doesn't change.
Using Ampere's Law, the magnetic field produced inside this solenoid is given by
B = uo N I / h
where uo is the vacuum permeability, N is the number of turns in the solenoid and h is the length of the solenoid. Earth's magnetic field is around 50 microteslas in North America thus the current needed in the solenoid is
I = B h / (uo N) = (50 E-6 ) (4) / ((4 pi E-7)(6000) ) = 0.026 A
I = 26 mA
So you need a current of around 26 mA.
The right answer is B because a liquid can take the shape of anything its in but it has the same volume