When a charged particle moves in a uniform magnetic field, the magnetic force acts as a centripetal force, causing the particle to move in a circular path. By equating the magnetic force to the centripetal force, we can derive an expression for the radius of curvature and determine its proportionality to various physical quantities.
Correct Option: B) Momentum of the particle
The question asks to identify the type of materials that are attracted to magnets. This requires understanding the basic classification of magnetic materials based on their interaction with an external magnetic field.
Correct Option: A) Ferromagnetic materials are strongly attracted to magnets due to the alignment of their magnetic domains with the external magnetic field. They can also retain magnetism after the external field is removed.
The question asks to identify a natural magnet from the given options. A natural magnet is a material found in nature that exhibits magnetic properties without being artificially magnetized.
Correct Option: A) Magnetite is a naturally occurring mineral (\(\text{Fe}_3\text{O}_4\)) that exhibits strong magnetic properties, making it a natural magnet.
The question asks about the direction of magnetic field lines outside a bar magnet. Understanding the convention for magnetic field lines is key to answering this question.
Correct Option: A) From North to South
Outside a bar magnet, magnetic field lines always originate from the North pole and enter the South pole, thus flowing from North to South.
The question asks about the effect of heating on a magnet. This relates to the fundamental properties of magnetic materials and how temperature influences their magnetic domains.
B) It demagnetizes the magnet. Heating a magnet increases the thermal energy of its constituent atoms, causing their magnetic domains to become misaligned and randomized, thus reducing or destroying its magnetic properties.
The question asks to identify the material with high magnetic permeability. Magnetic permeability is a measure of how easily a material can be magnetized or how much it concentrates magnetic flux lines. Materials are classified based on their magnetic properties into diamagnetic, paramagnetic, and ferromagnetic substances. Ferromagnetic materials are known for their high magnetic permeability.
C) Iron — Iron is a classic example of a ferromagnetic material. Ferromagnetic materials like iron have domains that align with an external magnetic field, leading to a strong internal magnetic field and thus a very high magnetic permeability. This property makes iron and its alloys suitable for applications like electromagnets, transformer cores, and magnetic shielding.