Which statement best describes the historical link between electricity and magnetism?

Which statement best describes the historical link between electricity and magnetism?

• A. A compass deflects due to gravity near a current
• B. A compass deflects when a wire carries current
• C. A compass deflects only in Earth's magnetic field
• D. Electricity and magnetism are unrelated

Answer: (B)

Electricity and magnetism are deeply connected because moving electric charges create magnetic fields. The famous turning point was the observation that a compass needle deflects when a wire carries current. The current generates a magnetic field that wraps around the wire, and the compass needle, being a tiny magnet, aligns with that field, causing deflection. This shows why the correct statement is the best one: the deflection comes from the magnetic field produced by the electric current, not from gravity or Earth's field alone. The direction of deflection depends on the current direction, a fact you can predict with the right-hand rule. This discovery helped establish electromagnetism and explains how electric devices like motors and generators work. The other ideas don’t fit because gravity doesn’t produce a magnetic effect on a compass, the field in question isn’t limited to Earth’s field, and electricity and magnetism aren’t unrelated phenomena—they’re two aspects of the same fundamental interaction.

Electricity and magnetism are deeply connected because moving electric charges create magnetic fields. The famous turning point was the observation that a compass needle deflects when a wire carries current. The current generates a magnetic field that wraps around the wire, and the compass needle, being a tiny magnet, aligns with that field, causing deflection.

This shows why the correct statement is the best one: the deflection comes from the magnetic field produced by the electric current, not from gravity or Earth's field alone. The direction of deflection depends on the current direction, a fact you can predict with the right-hand rule. This discovery helped establish electromagnetism and explains how electric devices like motors and generators work.

The other ideas don’t fit because gravity doesn’t produce a magnetic effect on a compass, the field in question isn’t limited to Earth’s field, and electricity and magnetism aren’t unrelated phenomena—they’re two aspects of the same fundamental interaction.