The correct option is (b).
Explanation
The magnetic effect of electric current, first demonstrated by Hans Christian Oersted. When an electric current flows through a conductor, it generates a magnetic field around it. This magnetic field can exert a force on a magnetic compass needle placed nearby, causing it to deflect.
Statement-wise Analysis:
- Statement 1 is Incorrect: A magnetic compass is a sensitive device capable of detecting even small amounts of electric current. In experimental setups (such as testing conductivity in liquids), a standard electric bulb may not glow if the current is too weak due to insufficient heating of the filament. However, a magnetic compass placed near the wire will still show deflection because the magnetic effect is produced even by weak currents. Therefore, it is often used as a tester for weak currents.
- Statement 2 is Correct: The strength of the magnetic field produced around a straight current-carrying conductor is directly proportional to the magnitude of the current flowing through it ($B \propto I$). Consequently, a larger current produces a stronger magnetic field, which exerts a greater torque on the magnetic needle, resulting in a larger deflection (up to the point of alignment with the field).
Key Takeaway:
Electric current produces a magnetic field capable of deflecting a magnetic compass. The extent of this deflection is directly related to the magnitude of the current; even weak currents can cause visible deflection, making a magnetic compass a useful indicator in low-current circuits.