Question

a compass needle normally points toward earths magnetic pole, which is near the north pole. which best explains why the needle moves away from the pole when it comes close to a current - carrying wire?
current within the wire weakens the magnetic force of the pole.
magnetism surrounding the wire weakens the magnetic force of the pole.
current within the wire draws the needle toward the wire.
magnetism surrounding the wire draws the needle toward the wire.

Explanation:

To solve this, we recall the principle of electromagnetism: a current - carrying wire produces a magnetic field (magnetism) around it. A compass needle is a small magnet that aligns with magnetic fields.

1. Analyze option A: A current - carrying wire does not weaken the magnetic force of the Earth's magnetic pole. The Earth's magnetic pole's force is a separate magnetic field, and the wire's current doesn't directly weaken the pole's force. So A is incorrect.
2. Analyze option B: Similar to A, the magnetism around the wire does not weaken the magnetic force of the Earth's pole. The two magnetic fields (from the Earth and the wire) interact with the compass needle, not with each other in a way that weakens the pole's force. So B is incorrect.
3. Analyze option C: The current in the wire itself does not draw the needle. It is the magnetic field produced by the current - carrying wire that interacts with the compass needle. So C is incorrect.
4. Analyze option D: A current - carrying wire produces a magnetic field (magnetism) around it. The compass needle, being a magnet, will align with the resultant magnetic field from the Earth and the wire. When near the wire, the magnetic field from the wire exerts a force on the compass needle, drawing it toward the wire (since the needle aligns with the wire's magnetic field), causing it to move away from the Earth's magnetic pole. So D is correct.

Answer:

D. Magnetism surrounding the wire draws the needle toward the wire.