Statement I : A compass needle placed near a current-carrying wire will get deflected. Statement II : A current-carrying wire creates magnetic field around it.
- A.Both the statements are individually true and Statement II is the correct explanation of Statement I
- B.Both the statements are individually true but Statement II is not the correct explanation of Statement I
- C.Statement I is true but Statement II is false
- D.Statement I is false but Statement II is true
Correct answer
Explanation
The correct answer is A. Both statements are true, and the magnetic field set up by the current (Statement II) is exactly why the compass needle turns (Statement I).
In 1820 the Danish physicist Hans Christian Oersted noticed that a compass needle kept near a wire swung whenever current flowed through the wire. This was the first proof that electricity and magnetism are linked. A current-carrying straight conductor produces a magnetic field whose lines form concentric circles around the wire; their direction is given by the right-hand thumb rule. A compass needle is a small magnet, so it lines up with this new field and is deflected. Reversing the current reverses the deflection, and a stronger current gives a stronger field.
B is wrong: Statement II is the very cause of Statement I, so it does explain it.
C is wrong: Statement II is true.
D is wrong: Statement I is true, as Oersted's experiment shows.
Exam tip: Oersted (1820): current → magnetic field → compass deflects; field direction by the right-hand thumb rule.
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