Grade 9 Physics - Magnetism

What is the property of a material that allows it to create a magnetic field?

• Thermoelectricity

• Diamagnetism

• Paramagnetism

• Ferromagnetism

Explain the difference between a permanent magnet and an electromagnet.

• A permanent magnet can be turned on and off, while an electromagnet cannot.

• A permanent magnet is made of plastic, while an electromagnet is made of metal.

• The main difference between a permanent magnet and an electromagnet is that a permanent magnet retains its magnetic properties without the need for an external magnetic field, while an electromagnet only exhibits magnetic properties when an electric current flows through it.

• A permanent magnet is only used in industrial applications, while an electromagnet is used in household appliances.

How does the Earth's magnetic field affect a compass needle?

• The Earth's magnetic field causes the compass needle to align with the magnetic field lines.

• The Earth's magnetic field repels the compass needle.

• The Earth's magnetic field causes the compass needle to spin uncontrollably.

• The Earth's magnetic field has no effect on the compass needle.

State the right-hand rule for determining the direction of the magnetic field around a current-carrying wire.

• Curl your fingers in the direction of the current flow to determine the magnetic field direction.

• Twist your wrist in the direction of the current flow to determine the magnetic field direction.

• Point your fingers in the direction of the current flow to determine the magnetic field direction.

• Extend your arm in the direction of the current flow to determine the magnetic field direction.

What is the unit of measurement for magnetic field strength?

• Tesla (T)

• Newton (N)

• Gauss (G)

• Ampere (A)

Describe how magnetic field lines are oriented around a bar magnet.

• The magnetic field lines around a bar magnet are oriented from the north pole to the south pole outside the magnet, forming closed loops. Inside the magnet, the field lines travel from the south pole to the north pole.

• The magnetic field lines around a bar magnet are oriented from the east pole to the west pole.

• Magnetic field lines around a bar magnet are oriented in a straight line from one end to the other.

• Field lines around a bar magnet are oriented in a spiral pattern.

What is magnetic declination and how does it affect navigation using a compass?

• Magnetic declination is the angle between magnetic north and true north at a specific location. It affects navigation using a compass by causing the needle to point slightly off true north, requiring adjustments to accurately navigate.

• Magnetic declination is the force that pulls objects towards the magnetic poles, affecting compass accuracy.

• Magnetic declination is the term used to describe the process of aligning a compass with true north.

• Magnetic declination is the angle between magnetic north and the equator, impacting compass readings.

Explain the concept of magnetic induction.

• Magnetic induction is the process of creating a magnetic field by rubbing two magnets together.

• Magnetic induction is the process of converting electricity into magnetism.

• Magnetic induction is the process of attracting metal objects using a magnetic force.

• Magnetic induction is the process by which a material or object becomes magnetized when exposed to a magnetic field.

What is the difference between ferromagnetic, paramagnetic, and diamagnetic materials?

• Ferromagnetic materials have strong permanent magnetic properties, paramagnetic materials are weakly attracted to magnetic fields, and diamagnetic materials are weakly repelled by magnetic fields.

• Diamagnetic materials are strongly attracted to magnetic fields

• Ferromagnetic materials are weakly attracted to magnetic fields

• Paramagnetic materials have strong permanent magnetic properties

How can the strength of an electromagnet be increased?

• By increasing the number of turns in the coil, increasing the current flowing through the coil, and using a core material with high magnetic permeability.

• Using a core material with low magnetic permeability

• Decreasing the number of turns in the coil

• Decreasing the current flowing through the coil