Magnetism and Electromagnetism Quiz

Permanent magnetism is the ability of a material to produce a magnetic field continuously, while induced magnetism occurs when a material temporarily becomes a magnet when placed in a magnetic field but loses its magnetism once removed from the field.

The magnetic field around a bar magnet forms closed loops, running from the north pole to the south pole outside the magnet, and from the south pole to the north pole inside the magnet. The field lines are denser at the poles.

A magnetic force acts on a moving charged particle in a direction perpendicular to both the velocity of the particle and the magnetic field, causing the particle to follow a circular or spiral path.

Fleming's Left-Hand Rule states that if you align your left hand with the thumb, forefinger, and middle finger at right angles to each other, with the forefinger pointing in the direction of the magnetic field, the thumb in the direction of the current, then the middle finger shows the direction of the force on the conductor. It is used to determine the direction of the force in an electric motor.

The commutator in an electric motor reverses the direction of the current in the coil as it spins, ensuring the force on the coil remains in the same direction, thus enabling continuous rotation.

A loudspeaker works by using a coil of wire placed in a magnetic field. When an alternating current flows through the coil, it creates a varying magnetic field that interacts with the permanent magnet, causing the coil and attached diaphragm to vibrate and produce sound.

A transformer increases or decreases the voltage of alternating current (AC) by using two coils of wire wound around a magnetic core. The number of turns in the coils determines whether the transformer steps up or steps down the voltage.

Induced potential refers to the voltage generated in a coil of wire when it is exposed to a changing magnetic field, due to electromagnetic induction. This is the principle behind generators and transformers.

When the voltage is stepped down in a transformer, the current in the primary coil decreases, while the current in the secondary coil increases, maintaining the same power (assuming an ideal transformer).

The direction of the magnetic field around a current-carrying wire can be determined using the right-hand rule. When you hold the wire with your right hand, with your thumb pointing in the direction of the current, your fingers will curl around the wire, showing the direction of the magnetic field.