Which of the following statements is true about magnetic fields and electric currents?
A. Electric currents always produce magnetic fields.
B. Magnetic fields always produce electric currents.
C. Magnetic fields are unrelated to electric currents.
D. Magnetic fields can only be produced by permanent magnets.
The correct answer and explanation is:
The correct answer is A. Electric currents always produce magnetic fields.
Explanation:
Magnetic fields and electric currents are deeply connected, as described by Ampère’s law, which states that an electric current produces a magnetic field. This is a fundamental principle of electromagnetism. The relationship between electricity and magnetism is one of the cornerstones of classical physics.
When an electric current flows through a conductor, such as a wire, it generates a magnetic field around the wire. The direction of the magnetic field depends on the direction of the current flow and can be determined using the right-hand rule. According to this rule, if you hold your right hand with your thumb pointing in the direction of the current, your fingers will curl in the direction of the magnetic field.
This phenomenon is not limited to just wires; it occurs whenever there is a movement of electric charge, which could be in the form of current or even electron motion. For example, in an electromagnet, when current flows through a coil of wire, a magnetic field is generated around the coil, turning the coil into a magnet.
On the other hand, magnetic fields do not necessarily always produce electric currents, which debunks option B. While it is true that changing magnetic fields can induce electric currents (as in Faraday’s Law of Induction), a steady magnetic field on its own will not create current.
Additionally, magnetic fields are not unrelated to electric currents (option C) because they are inherently linked, and magnetic fields can be produced by both electric currents and magnets, not just permanent magnets (option D). Hence, option A is the accurate statement.