1.
Describe a magnetic field
Correct Answer
B. Surrounds a magnet pointing from north pole to south pole and causes the force that attracts or repels a magnet
Explanation
A magnetic field is a region of space that surrounds a magnet and is characterized by the direction of the force it exerts on other magnets. It points from the north pole to the south pole of the magnet and is responsible for the attraction or repulsion between magnets.
2.
Every magnetic field has poles: true or false
Correct Answer
A. True
Explanation
Every magnetic field has poles. This is because a magnetic field is created by a magnet or a moving electric charge, and both of these sources have poles. The poles of a magnet are the regions where the magnetic field is strongest, and they are referred to as the North and South poles. Therefore, it is true that every magnetic field has poles.
3.
An atom is:
Correct Answer
A. The smallest magnet
Explanation
An atom can be considered the smallest magnet because it consists of charged particles, such as protons and electrons, which create magnetic fields. These magnetic fields result from the movement of the charged particles within the atom. While individual atoms may not exhibit strong magnetic properties, they can align their magnetic fields in certain materials to create larger magnetic effects. Therefore, an atom can be seen as the smallest unit that possesses magnetic properties.
4.
A magnetic domain :
Correct Answer
A. Requires a group of atoms with the magnetic fields lined up in the same direction
Explanation
A magnetic domain requires a group of atoms with the magnetic fields lined up in the same direction. This is because the alignment of magnetic fields in the same direction creates a stronger overall magnetic field. When the magnetic fields of atoms within a material are randomly oriented, the material does not exhibit strong magnetic properties. However, when the atoms align their magnetic fields, it creates regions of strong magnetization known as magnetic domains. These domains contribute to the overall magnetic behavior of the material.
5.
Earth is a magnet and has a magnetic field: true or false
Correct Answer
A. True
Explanation
Earth is indeed a magnet and has a magnetic field. This is due to the presence of the Earth's solid inner core, which is primarily made up of iron and nickel. The rotation of the Earth generates electric currents in the liquid outer core, which in turn creates a magnetic field. This magnetic field extends from the Earth's interior into space and is responsible for various phenomena such as the Earth's magnetic poles and the protection of our planet from harmful solar radiation.
6.
What causes earth magnetic field
Correct Answer
C. The motion of magma near the earths core
Explanation
The motion of magma near the earth's core causes the Earth's magnetic field. As the liquid iron in the outer core moves, it generates electric currents, which in turn create a magnetic field. This magnetic field extends from the core to the surface of the Earth, creating the Earth's magnetic field.
7.
How often does the earths magnetic field change directions
Correct Answer
A. Every four to five thousand years
Explanation
The Earth's magnetic field changes directions every four to five thousand years. This phenomenon, known as geomagnetic reversal, occurs when the magnetic north and south poles switch places. This process is gradual and can take thousands of years to complete. Evidence of these reversals can be found in the geological record, such as in the alignment of magnetic minerals in rocks. This regular pattern of magnetic field reversals provides valuable information for scientists studying Earth's history and geology.
8.
Define magnet
Correct Answer
B. A material that attracts other magnets
Explanation
The correct answer is "a material that attracts other magnets." This definition accurately describes a magnet as a material that has the ability to attract other magnets. It implies that magnets have a magnetic field that can exert a force on other magnetic materials, causing them to be drawn towards each other.
9.
Like magnetic poles
Correct Answer
A. Repel
Explanation
Like magnetic poles repel each other because they have the same type of charge. According to the laws of magnetism, opposite poles attract each other, while like poles repel each other. This is due to the magnetic field lines that surround the magnets. When two magnets with the same pole are brought close together, their magnetic fields interact and push each other away, resulting in repulsion.
10.
Describe a magnetic field
Correct Answer
B. Surrounds a magnet pointing from north pole to south pole and causes the force that attracts or repels a magnet
Explanation
A magnetic field is a region in space where magnetic forces are exerted. It surrounds a magnet and extends from its north pole to its south pole. This magnetic field is responsible for the force that attracts or repels other magnets.
11.
An atom is:
Correct Answer
A. The smallest magnet
Explanation
An atom is the smallest unit of a chemical element that retains the properties of that element. It consists of a nucleus, which contains positively charged protons and neutral neutrons, surrounded by negatively charged electrons. While atoms do possess certain magnetic properties due to the movement of electrons, it would be more accurate to say that atoms can behave as tiny magnets rather than being the smallest magnet in itself.
12.
A magnetic domain :
Correct Answer
A. Requires a group of atoms with the magnetic fields lined up in the same direction
Explanation
A magnetic domain refers to a region within a material where the magnetic moments of atoms are aligned in the same direction. This alignment occurs due to the interaction between neighboring atoms and their magnetic fields. Therefore, a magnetic domain requires a group of atoms with their magnetic fields lined up in the same direction. This alignment allows the material to exhibit magnetic properties.
13.
Earth is a magnet and has a magnetic field: true or false
Correct Answer
A. True
Explanation
Earth is a magnet and has a magnetic field because it has a solid iron core surrounded by a molten outer core. The movement of these molten metals creates electric currents, which in turn generate a magnetic field. This magnetic field extends from the Earth's interior into space and is responsible for various phenomena, such as the alignment of compass needles and the protection of the planet from harmful solar radiation.
14.
The earths magnetic field
Correct Answer
A. Deflects charged particles from the sun and is used to determine direction by humans and animals
Explanation
The earth's magnetic field deflects charged particles from the sun, such as solar wind and cosmic rays, preventing them from directly hitting the Earth's surface. This is important for the protection of life on Earth as these particles can be harmful. Additionally, the magnetic field plays a crucial role in navigation. Animals, such as birds and sea turtles, can sense the Earth's magnetic field and use it to navigate during migration. Humans have also developed compasses that utilize the Earth's magnetic field to determine direction.
15.
What is used to increase or decrease the voltage in ac system
Correct Answer
A. Transformers
Explanation
Transformers are used to increase or decrease the voltage in an AC system. They work based on the principle of electromagnetic induction, where an alternating current in the primary coil creates a changing magnetic field, which in turn induces a voltage in the secondary coil. This allows the voltage to be stepped up or down depending on the number of turns in each coil. Voltmeters, on the other hand, are used to measure the voltage in a circuit and do not have the capability to alter or modify the voltage.
16.
A material that attracts iron and materials that contain iron is called a(n)
Correct Answer
C. Magnet
Explanation
A material that attracts iron and materials that contain iron is called a magnet. Magnets have the ability to exert a force on iron objects and other materials that have iron in them. This attraction is due to the magnetic field produced by the magnet, which interacts with the magnetic properties of iron. Magnets can be natural, like lodestone, or man-made, like permanent magnets. They are commonly used in various applications, such as in compasses, electric motors, and magnetic storage devices.
17.
The area of a magnet where the magnetic force is strongest is a
Correct Answer
A. Magnetic pole
Explanation
A magnetic pole is the area of a magnet where the magnetic force is strongest. It is the region where the magnetic field lines converge or diverge, indicating the direction of the magnetic field. The strength of the magnetic force is highest at the poles of a magnet, and it decreases as you move away from the poles. Therefore, the correct answer is magnetic pole.
18.
If two magnets were in this order: NS SN they would:
Correct Answer
A. Repel
Explanation
When two magnets are arranged in the order NS SN, they would repel each other. This is because like poles (N and N or S and S) repel each other, causing the magnets to push away from each other. Therefore, in this arrangement, the magnets would exert a repulsive force and move apart from each other.
19.
The smallest particle of an element is known as an:
Correct Answer
D. Atom
Explanation
An atom is the smallest particle of an element. It consists of protons, neutrons, and electrons. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge. Atoms are the basic building blocks of matter and combine to form molecules and compounds.
20.
A particle that does not carry an electrical charge is a:
Correct Answer
B. Neutron
Explanation
A neutron is a subatomic particle that does not carry an electrical charge. Unlike protons and electrons, which have positive and negative charges respectively, neutrons are electrically neutral. They are found in the nucleus of an atom along with protons, and their main role is to contribute to the mass of the atom without affecting its charge. Neutrons play a crucial role in determining the stability and behavior of atoms, particularly in nuclear reactions.
21.
A ferromagnetic material is:
Correct Answer
A. A material that shows strong magnetic effects
Explanation
A ferromagnetic material is a material that shows strong magnetic effects. This means that when placed in a magnetic field, the material becomes strongly magnetized and retains its magnetization even after the external field is removed. This behavior is due to the alignment of the magnetic moments of the atoms or ions in the material, resulting in a net magnetic field. Examples of ferromagnetic materials include iron, nickel, and cobalt.
22.
A magnet made of a material that keeps its magnetism is known as a:
Correct Answer
C. Permanent magnet
Explanation
A magnet made of a material that keeps its magnetism is known as a permanent magnet. Unlike temporary magnets, which only exhibit magnetism when in the presence of a magnetic field, permanent magnets retain their magnetism even when the external magnetic field is removed. This is due to the alignment of the magnetic domains within the material, which creates a persistent magnetic field. Permanent magnets are commonly used in various applications such as generators, motors, and magnetic storage devices.
23.
If two magnets were in this order: NS NS they would:
Correct Answer
B. Attract
Explanation
If two magnets are arranged in the order NS NS, they would attract each other. This is because opposite poles attract each other, and in this case, the north pole of one magnet is facing the south pole of the other magnet. Therefore, they would attract each other.
24.
The Earth's magnetic field
Correct Answer
A. Deflects charged particles from the sun and is used to determine direction by humans and animals
Explanation
The Earth's magnetic field deflects charged particles from the sun, preventing them from directly hitting the Earth's surface. This protection is crucial as these particles can be harmful to both humans and animals. Additionally, the Earth's magnetic field is used by humans and animals to determine direction. Many animals, such as migratory birds, rely on the Earth's magnetic field for navigation during their long journeys. Similarly, humans use compasses, which work based on the Earth's magnetic field, to determine direction when traveling.
25.
What device is used to increase or decrease the voltage in ac system?
Correct Answer
A. Transformers
Explanation
Transformers are devices used to increase or decrease the voltage in an AC system. They work on the principle of electromagnetic induction, where the primary coil receives the input voltage and produces a magnetic field. This magnetic field induces a voltage in the secondary coil, which can be either higher or lower than the input voltage depending on the turns ratio of the transformer. Transformers are commonly used in power distribution systems to step up the voltage for long-distance transmission and step it down for consumer use.
26.
Every magnetic field has poles: true or false
Correct Answer
A. True
Explanation
Every magnetic field has poles because a magnetic field is created by a magnet or a current-carrying wire, and both magnets and wires have two poles - a north pole and a south pole. The magnetic field lines always flow from the north pole to the south pole, forming a closed loop. Therefore, it can be concluded that every magnetic field has poles.
27.
What causes Earth's magnetic field
Correct Answer
C. The motion of magma near the earths core releasing electrons.
Explanation
The correct answer is "The motion of magma near the earth's core releasing electrons." The Earth's magnetic field is generated by the movement of molten iron and nickel in the outer core of the planet. This motion creates electric currents, which in turn generate a magnetic field. As the magma moves, electrons are released, creating a flow of electric charges that generates the Earth's magnetic field. The alignment of the magnetic fields of the atoms in the core is not the cause of the Earth's magnetic field. The Coriolis effect, on the other hand, is related to the rotation of the Earth and its impact on atmospheric and oceanic currents, but it is not the cause of the magnetic field.
28.
How often does the earths magnetic field change directions
Correct Answer
A. Every four to five thousand years
Explanation
The Earth's magnetic field changes directions every four to five thousand years. This phenomenon is known as geomagnetic reversal, where the magnetic north and south poles switch places. This change occurs gradually over thousands of years and has been observed through geological records and studies of ancient rocks. These reversals have important implications for navigation systems, as well as for understanding the Earth's geological history and its impact on climate and life on Earth.
29.
How can you make a magnet temporarily lose its magnetism?
Correct Answer
A. By heating it or hitting/dropping it really hard.
Explanation
When a magnet is heated, the thermal energy disrupts the alignment of the magnetic domains within the magnet, causing them to become disordered. This disordered arrangement reduces the overall magnetic field and makes the magnet lose its magnetism temporarily. Similarly, hitting or dropping the magnet really hard can also disrupt the alignment of the magnetic domains, causing the magnet to lose its magnetism temporarily. Blowing on it or making it cold does not have the same effect on the alignment of magnetic domains, so they do not cause the magnet to lose its magnetism.
30.
A tiny, negatively charged particle that usually exists in the outer region of an atom is called:
Correct Answer
B. Electron
Explanation
An electron is a tiny, negatively charged particle that usually exists in the outer region of an atom. It has a negligible mass compared to protons and neutrons, and it orbits around the nucleus of an atom. Electrons play a crucial role in determining the chemical properties and behavior of elements, as they are involved in chemical bonding and the formation of compounds.