Simple phenomena of magnetism

(a) Two north poles repel each other.
(b) A north pole and a south pole attract each other.
(c) A magnet and an unmagnetised piece of iron attract each other. The magnet induces magnetism in the iron, creating a temporary opposite pole closest to the magnet, leading to attraction.

(a) False. Like poles repel.
(b) False. Unlike poles attract.
(c) False. Magnets can attract magnetic materials like iron, steel, nickel and cobalt.

When an unmagnetized iron nail is brought close to a strong permanent magnet, the magnetic domains within the nail align with the magnetic field of the magnet. This alignment causes the nail to become magnetized, with the end closest to the magnet developing the opposite polarity. This effect is temporary; the nail loses its magnetism when the permanent magnet is removed. The nail is temporarily magnetised.

1. Iron
2. Steel (while it can be magnetized more permanently, it does exhibit induced magnetism)

When the external magnetic field is removed:
* Soft iron: Loses almost all of its magnetism very quickly. The domains within the iron return to a random arrangement easily.
* Steel: Retains a significant portion of its magnetism. The domains within the steel are more resistant to returning to a random arrangement, resulting in a permanent magnet.

Magnetic: Iron, Nickel, Cobalt.
Non-Magnetic: Wood, Plastic, Aluminium. Magnetic materials are typically ferromagnetic elements, while non-magnetic materials do not exhibit this property.

The compass needle is itself a small magnet. When placed in a magnetic field (like the one surrounding the bar magnet), it experiences a force. This force causes the compass needle to rotate until it aligns with the direction of the magnetic field lines at that point, minimizing the potential energy.

A drawing should show closed loops emerging from the North pole and entering the South pole of the bar magnet. The field lines should be more concentrated near the poles, indicating a stronger magnetic field. Arrows on the field lines should point from North to South.

1. Place the bar magnet on a piece of paper.
2. Place the plotting compass near one pole of the magnet.
3. Mark the direction of the compass needle with two dots.
4. Move the compass so the tail of the needle is on the previous dot and mark the new position of the compass needle with another dot.
5. Repeat step 4 multiple times to create a chain of dots.
6. Connect the dots to draw a magnetic field line.
7. Repeat steps 2-6 at different locations around the magnet to map the field pattern.

The North pole of the compass needle will align itself with the direction of the magnetic field at its location. Therefore, the compass needle points in the direction of the force that would act on a North pole placed at that point, effectively mapping the magnetic field lines.

1. Place the compass at the point where you want to determine the field direction.
2. Allow the compass needle to settle.
3. The north pole of the compass needle will point in the direction of the magnetic field at that point. This is because the compass needle aligns itself with the magnetic field lines.

Sprinkle iron filings evenly onto a sheet of paper or plastic placed over the bar magnet. Gently tap the sheet. The iron filings will align themselves along the magnetic field lines, showing the shape and direction of the field. The filings concentrate where the field is strongest (near the poles).

1. Refrigerator Magnets: Holding notes and decorations onto metallic surfaces.
2. Compass Needles: Aligning with the Earth's magnetic field to indicate direction.
3. Loudspeakers: Interacting with electromagnets to produce sound.
(Each correct use = 1 mark)

1. Electric Bells: To strike a bell when the circuit is closed.
2. Cranes in scrap yards: Lifting heavy ferrous materials.
3. Relays: Acting as a switch to control another circuit.
(Each correct use = 1 mark)

Magnetic forces arise from the interaction of their magnetic fields. If opposite poles (N and S) face each other, their magnetic field lines link, resulting in an attractive force. If like poles (N and N, or S and S) face each other, their magnetic field lines are distorted, resulting in a repulsive force.

Each wire creates a circular magnetic field around itself. Since the currents are in opposite directions, the magnetic fields between the wires point in opposite directions. This interaction of the magnetic fields results in a repulsive force between the wires. Specifically, the field of one wire exerts a force on the current in the other wire, pushing them apart.

The closer the magnetic field lines are to each other, the stronger the magnetic field. Conversely, the farther apart the field lines are, the weaker the magnetic field. A higher density of field lines indicates a stronger magnetic force.

The magnetic field strength is stronger at Point A because the magnetic field lines are closer together. The magnetic field strength is weaker at Point B because the magnetic field lines are spread further apart. A denser concentration of field lines means a stronger field.