Test: Electromagnetism - SSS 1 MCQ

Lenz's law states that the induced current will flow in a direction that opposes the change in magnetic flux that caused it, which is a manifestation of the conservation of energy.

An electric bell functions by converting electrical energy into mechanical energy, causing the hammer to strike the bell when the circuit is closed, which is a practical application of electromagnetism.

A solenoid generates a temporary magnetic field when an electric current flows through it, making it crucial for applications such as electromagnets, which can be turned on and off as needed.

A transformer is designed to change the voltage of alternating current without altering its frequency, making it essential for efficient power distribution over long distances.

Inserting a soft iron core into a solenoid enhances the magnetic field strength significantly due to the increased magnetic permeability of the iron, making the solenoid more effective as an electromagnet.

The speed of rotation of a coil in a motor can be increased by enhancing the strength of the magnetic field, along with increasing the current and the number of turns in the coil, as these factors all contribute to the force exerted on the coil.

Hans Oersted discovered that a wire carrying electric current generates a magnetic field around it, demonstrating the relationship between electricity and magnetism. This foundational observation paved the way for the field of electromagnetism.

Lenz's law describes that the induced current will flow in a direction that opposes the change in magnetic flux that produced it, ensuring conservation of energy and stability in electromagnetic systems.

Electromagnetic induction occurs when there is a change in the magnetic field around a conductor, leading to the generation of an electromotive force (emf) in the conductor, which is a foundational principle in electricity generation.

A current-carrying solenoid exhibits magnetic field lines similar to those of a bar magnet, allowing it to align in a north-south direction when freely suspended, showcasing its magnetic properties.

Increasing the current in a solenoid strengthens its magnetic field, which is evidenced by denser magnetic field lines. This principle is crucial for applications like electromagnets and transformers.

In the right-hand thumb rule, the thumb points in the direction of the electric current, while the fingers curl around the wire in the direction of the magnetic field lines. This rule helps visualize the orientation of magnetic fields created by currents.

Reversing the direction of current in a wire causes the compass needle to deflect in the opposite direction while the pattern of iron filings remains the same, illustrating the magnetic field's dependence on current direction.

Electromagnets can generate stronger magnetic fields compared to permanent magnets and allow for easy adjustment of strength and polarity by changing the current or the number of coil turns.

An AC generator produces alternating current (AC), which periodically reverses direction, unlike direct current (DC), which flows in a single direction. This alternating nature allows for efficient long-distance power transmission.

When a conductor is placed parallel to a magnetic field, it experiences no force because the force on the conductor is dependent on the angle between the current direction and the magnetic field; parallel alignment results in zero perpendicular interaction.

Fleming's left-hand rule is used to determine the direction of the force on a current-carrying conductor in a magnetic field by correlating the directions of current, magnetic field, and force.

Increasing the strength of the current in a solenoid results in denser magnetic field lines, indicating a stronger magnetic field which improves the solenoid's effectiveness as an electromagnet.

The induced emf in an AC generator is directly proportional to the speed of rotation of the coil; faster rotation leads to a greater change in magnetic flux and therefore a higher induced emf.

A step-up transformer features more turns in the secondary coil than in the primary coil, which allows it to increase the voltage of the incoming alternating current.