Question

assuming a current is flowing, what increases the strength of the magnetic field of a coiled electrical wire?
straightening the wire
changing the direction of the current flow
adding more coils to the wire
stopping the current

Explanation:

• Straightening the wire reduces the number of loops, so the magnetic field strength decreases.
• Changing the direction of the current flow changes the direction of the magnetic field but not its strength.
• Stopping the current means there is no magnetic field (since a current - carrying wire produces a magnetic field).
• For a coiled electrical wire (solenoid - like), the magnetic field strength \(B=\mu_0nI\) (where \(n=\frac{N}{L}\) is the number of turns per unit length, \(N\) is the number of turns, \(L\) is the length of the coil, \(I\) is the current, and \(\mu_0\) is the permeability of free space). Adding more coils (\(N\) increases) while keeping other factors (like current \(I\) and length \(L\) if we assume we just add coils in the same length) increases \(n\), and thus increases the magnetic field strength.

Answer:

adding more coils to the wire