Magnetism and Electromagnetism - SS1 Physics Past Questions and Answers - page 2
Describe the concept of magnetic field and its properties. How is a magnetic field created, and what are its characteristics?
A magnetic field is a region in which a magnetic force can be detected. It is created by moving electric charges or by the presence of magnets. The properties of a magnetic field include direction, strength, and magnetic field lines.
The direction of a magnetic field is indicated by the north and south poles of a magnet. The strength of the magnetic field is determined by the proximity of the magnetic source. Magnetic field lines are imaginary lines that depict the direction and strength of the magnetic field. They form closed loops around a magnet, and the density of the field lines represents the strength of the field.
Explain the relationship between magnetic fields and electric currents. How does a current-carrying conductor create a magnetic field, and how is the direction of the field determined?
When an electric current flows through a conductor, it creates a magnetic field around the conductor. This phenomenon is known as Ampere's law. The magnetic field produced is circular and perpendicular to the direction of the current. The direction of the magnetic field can be determined using the right-hand rule. If you grasp the conductor with your right hand, such that your thumb points in the direction of the current, then the curled fingers indicate the direction of the magnetic field lines.
Which of the following materials is commonly used to make permanent magnets?
Copper
Aluminium
Iron
Plastic
What happens when a permanent magnet is heated to a high temperature?
Its magnetism becomes stronger.
Its magnetism becomes weaker.
It loses its magnetism.
Its magnetism remains unaffected.
How is the magnetism of a permanent magnet typically created?
By passing an electric current through it.
By exposing it to high temperatures.
By aligning its magnetic domains.
By applying a strong electric field.
Which of the following is an example of an electromagnet?
A refrigerator magnet.
A bar magnet.
A horseshoe magnet.
An MRI machine.
How can the strength of an electromagnet be increased?
By decreasing the current passing through it.
By increasing the number of coils in the wire.
By using a non-magnetic core material.
By decreasing the number of turns in the wire.
Compare and contrast permanent magnets and electromagnets. Discuss their similarities and differences.
Permanent magnets and electromagnets are two types of magnets with distinct characteristics and applications.
Similarities:
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Magnetic Field Generation: Both permanent magnets and electromagnets generate magnetic fields.
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Attraction and Repulsion: They exhibit attraction and repulsion based on their poles.
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Magnetic Properties: Both magnets can magnetise nearby magnetic materials.
Differences:
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Magnetism Generation: Permanent magnets have inherent magnetism due to their material composition, while electromagnets generate magnetism through the flow of electric current.
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Magnetism Control: The magnetism of permanent magnets cannot be easily controlled, while electromagnets can have their magnetic strength adjusted by varying the current.
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Strength: Permanent magnets generally have fixed magnetic strength, while the strength of an electromagnet can be adjusted as needed.
Electromagnetic induction is the process of:
Generating an electric field from a magnetic field
Generating a magnetic field from an electric field
Producing an electric current in a conductor by changing the magnetic field around it
Producing a magnetic field in a conductor by changing the electric field around it
The phenomenon of electromagnetic induction was first discovered by:
Michael Faraday
James Clerk Maxwell
Thomas Edison
Nikola Tesla