Which happens to the magnetic field of a wire when you change the direction of the current in the wire? the magnetic field
becomes stronger
also changes direction
becomes weaker

On a day when the barometer reads 75.23 cm, a reaction vessel holds 250 ml of ideal gas at 20 celsius. an oil manometer ( ρ= 810 kg/m^3) reads the pressure in the vessel to be 41 cm of oil and below atmospheric pressure. what volume will the gas occupy under s.t.p.?