Gibilisco: Magnetism MCQ! Trivia Quiz

An electromagnet can be switched on and off because it is created by passing an electric current through a coil of wire. By controlling the flow of current, the magnetic field produced by the electromagnet can be turned on or off. This allows for greater control and flexibility in its use compared to a permanent magnet, which always has a magnetic field.

The advantage of a magnetic disk compared to magnetic tape for data storage and retrieval is that data can be stored and retrieved more quickly with disks than with tapes. Magnetic disks have faster access and transfer times, allowing for quicker data retrieval and storage operations. This makes them more efficient for tasks that require frequent data access and manipulation, such as database management or real-time processing.

A magnetic hard disk is usually part of a computer because it is a storage device used to store and retrieve digital information. It is commonly found in desktops, laptops, and servers, where it provides a large capacity for storing files, software, and operating systems. The magnetic hard disk uses magnetic fields to store data on spinning platters, and it is accessed by the computer's operating system and other software to read and write data. Therefore, it is an essential component of a computer system.

A material that can be permanently magnetized is generally said to be ferromagnetic. Ferromagnetic materials have a high susceptibility to magnetic fields and can retain their magnetization even after the external magnetic field is removed. This is due to the alignment of the magnetic moments of the atoms within the material. Examples of ferromagnetic materials include iron, nickel, and cobalt.

The magnetic flux around a straight, current-carrying wire is strongest near the wire. This is because the magnetic field produced by the current-carrying wire follows a pattern of concentric circles around the wire. As we move farther away from the wire, the magnetic field lines spread out and become less concentrated, resulting in a weaker magnetic flux. Therefore, the magnetic flux is strongest near the wire.

The gauss is a unit of magnetic flux density. It measures the amount of magnetic field passing through a specific area. Magnetic flux density refers to the concentration of magnetic field lines in a given space, indicating the strength of the magnetic field. Ampere-turns measure the magnetomotive force, while overall magnetic field strength and magnetic power are not specific units of measurement.

The lines of magnetic flux originate at a north magnetic pole because magnetic field lines always form closed loops and flow from the north pole to the south pole. The north pole of a magnet is where the magnetic field lines emerge, while the south pole is where they converge. The lines of magnetic flux do not originate in atoms of ferromagnetic materials, at points where the lines are straight, or in electric charge carriers.

The magnetomotive force (MMF) is the force that creates a magnetic field in a magnetic circuit. It is given by the product of the number of turns in the coil and the current flowing through it. In this case, the coil has 10 turns and carries a current of 500 mA (0.5 A), so the MMF is 10 turns multiplied by 0.5 A, which equals 5.0 At (ampere-turns).

A commutator is a device that is used in a DC motor to reverse the direction of the current flow in the armature coil, thereby reversing the polarity of the magnetic field. This reversal of polarity allows the motor to continue rotating in the same direction. A solenoid is a coil of wire that produces a magnetic field when an electric current passes through it, but it does not reverse the polarity of the magnetic field. An armature coil is a part of the motor that interacts with the magnetic field to produce motion, but it does not reverse the polarity of the field. A field coil is a coil of wire that produces the main magnetic field in the motor, but it does not reverse the polarity of the field.

The geomagnetic field is responsible for making a compass work. A compass needle aligns itself with the Earth's magnetic field, allowing it to point towards the magnetic north pole. This field acts like a giant magnet, with magnetic lines of force running from the geographic south pole to the geographic north pole. The compass needle is magnetized and is able to align itself with these lines of force, enabling it to accurately indicate direction.

The given scenario describes a situation where a device only receives a signal when the relay coil carries current. In this case, the relay is functioning as a switch that is normally open, meaning the circuit is not complete and the device does not receive a signal unless the relay coil is energized.

A substance with high retentivity is well suited to making a permanent magnet because retentivity refers to the ability of a material to retain its magnetization even after the external magnetic field is removed. This means that the substance can maintain a strong magnetic field and effectively become a permanent magnet.

The correct answer is that geomagnetic lines of flux are horizontal at the geomagnetic equator. This is because the geomagnetic equator is the location where the Earth's magnetic field is parallel to the Earth's surface. As a result, the lines of flux run horizontally in this region. In contrast, at other latitudes, the lines of flux are tilted and become more vertical. Therefore, the statement "are horizontal at the geomagnetic equator" accurately describes the behavior of geomagnetic lines of flux in that specific location.

The force between a magnet and a piece of ferromagnetic metal that has not been magnetized is never repulsive. This is because the magnet and the metal have opposite magnetic poles, and opposite poles attract each other. Therefore, the force between them can only be attractive, not repulsive.

During a geomagnetic storm, multiple events can occur. Charged particles stream out from the sun, causing an increase in solar wind and impacting the earth's magnetic field. This disturbance in the earth's magnetic field can lead to various effects, such as auroras and disruptions in communication systems. Additionally, the strong magnetic fluctuations during a geomagnetic storm can induce electric currents in power transmission lines, potentially leading to disruptions in electrical power transmission. Therefore, it is possible for more than one of these events to occur during a geomagnetic storm.

The unit of overall magnetic field quantity is the maxwell. The maxwell is a unit of magnetic flux, which measures the total magnetic field passing through a given area. It is named after the physicist James Clerk Maxwell and is defined as the flux through one square centimeter of area perpendicular to a magnetic field of one gauss. The other options, gauss, tesla, and ampere-turn, are also units of magnetic field or related quantities, but they do not represent the overall magnetic field quantity as the maxwell does.

The presence of a magnetic field can always be attributed to the motion of electric charge carriers. When electric charges move, they create a magnetic field around them. This phenomenon is known as electromagnetism and is the basis for many everyday devices such as electric motors and generators. Ferromagnetic materials can also generate magnetic fields, but this is due to the alignment of their atomic magnetic moments rather than the motion of charge carriers. Diamagnetic materials do not generate magnetic fields on their own, and the north geomagnetic pole refers to the Earth's magnetic field rather than the cause of magnetic fields in general.

An AC electromagnet attracts pure, unmagnetized iron because when an alternating current flows through the coil of the electromagnet, it creates a changing magnetic field. This changing magnetic field induces a temporary magnetism in the iron, causing it to be attracted to the electromagnet. This attraction occurs regardless of the polarity of the iron or the electromagnet.

not-available-via-ai

A high tape-recorder motor speed is generally used for video recording and playback because video recording requires a fast motor speed to capture and reproduce the movement and details of the visuals accurately. This is especially important for smooth playback and high-quality video recordings. Voice recording and playback, as well as digital data storage and retrieval, do not necessarily require such high motor speeds as they primarily focus on capturing and reproducing audio or storing and retrieving data.