Gavin Pinto asked
“A current carrying wire is placed above a magnetic needle. What do you observe? If you want to increase this effect, what will you do? If you want to reverse the effect, what will you do?”
Ans: When a current carrying conductor is placed above a magnetic needle, the magnetic needle is deflected and tends to align itself perpendicular to the conductor. The effect can be increased by increasing the strength of current through the wire or by decreasing the distance.
However, the maximum deflection which can be produced is 90 degree, when the magnetic field produced by the current carrying wire is very much greater than the earth’s magnetic field.