The correct option is (c).
Explanation
The magnetic effect of electric current refers to the production of a magnetic field around a conductor carrying an electric current. This phenomenon was first demonstrated by Hans Christian Oersted in 1820, establishing the relationship between electricity and magnetism.
Statement-wise Analysis:
- Statement 1 is Correct: When electric current flows through a wire, it generates a magnetic field in the surrounding space. Consequently, the wire behaves like a magnet. This principle is the basis for the operation of electromagnets.
- Statement 2 is Incorrect: A compass needle is a small magnet free to rotate. Since a current-carrying wire produces a magnetic field, placing a compass near it results in an interaction between the wire's magnetic field and the compass needle. This causes the needle to deflect, rather than remain stationary.
- Statement 3 is Correct: The magnetic field generated by the wire is directly dependent on the flow of electric charges. Once the current is switched off, the source of the magnetic field is removed, and the magnetic effect ceases immediately.
Key Takeaway:
An electric current flowing through a conductor creates a temporary magnetic field around it, capable of deflecting a magnetic compass; this field vanishes when the current stops.