Explore topic-wise InterviewSolutions in .

No, because like poles repel each other, when two magnetic are brought close to each other.

Magnetic poles always exist in pairs and cannot: exist independently. If a bar magnet is broken into two or more pieces, each of them will have a north pole and a south pole. Hence, it is impossible to obtain a piece of magnet with only one magnetic pole.

Magnets that are made by humans from magnetic substances are called artificial magnets. They can be made in different shapes and sizes like bar magnet, horseshoe magnet, etc.

Bar magnet is a magnet in the shape of bar having two poles of equal and opposite pole strengths separated by certain distance (2l).

i. Magnetic lines of force originate from the north pole and end at the south pole. 

ii. The magnetic lines of force of a magnet or a solenoid form closed loops. This is in contrast to the case of an electric dipole, where the electric lines of force originate from the positive charge and end on the negative charge.

iii. The direction of the net magnetic field \(\vec{B}\) at a point is given by the tangent to the magnetic line of force at that point. 

iv. The number of lines of force crossing per unit area decides the magnitude of magnetic field \(\vec{B}\)

v. The magnetic lines of force do not intersect. This is because had they intersected, the direction of magnetic field would not be unique at that point.

The magnetic field around a magnet is shown by lines going from one end of the magnet to the other. These lines are named as magnetic lines of force.

The unit of magnetic intensity, H is Am^-1.

The degree to which a magnetic field can magnetise a material is represented in terms of magnetic intensity. 

Magnetic intensity of a material is the ratio of external magnetic field to the permeability of free space. 

Magnetic intensity of a material, H =B₀/μ₀, where B₀ - external magnetic field, μ₀ - permeability of free space.  

The answer is (D) MT^-1 C^-1 

The answer is (B) [L²A]

The answer is (C) Ferromagnetism

The answer is (C) ∈_r = 1.5, µ_r = 0.5

Declination at the place is the angle between true geographic north direction and the north shown by the magnetic compass needle. 

It is a point near the magnet where the magnetic field due to the magnet is equal and opposite to the horizontal component of magnetic field. The resultant magnetic field at the neutral point is zero.  

They are: 

(1) Magnetic declination (θ) at that place. 

(2) Magnetic inclination (I) dip at that place. 

(3) Horizontal comp of earths magnetic field (B_H) at that place. 

At magnetic equator 

Magnetic dip at a place is the angle between the earth’s total magnetic field at a place and horizontal drawn in magnetic meridian.

Z_E = B_EsinI or H_E = B_EcosI or tanI = Z_E/H_E

μ = μ₀μr. μ is the permeability of medium, μ₀ is permeability of free space, and μ_r is relative permeability of the medium. 

The unit of magnetisation is Am^-1.

We know that a circulating electron in an atom has a magnetic moment. In a bulk material, these moments add up vectorially and they can give a net magnetic moment which is non-zero. We define magnetisation M of a sample to be equal to its net magnetic moment per unit volume: 

M = m_net/V 

M is a vector with dimensions L A and is measured in a units of Am^-1. Consider a long solenoid of n turns per unit length and carrying a current I. The magnetic field in the interior of the solenoid was shown to be given by 

B₀ = μ₀ nI 

If the interior of the solenoid is filled with a material with non-zero magnetisation, the field inside the solenoid will be greater than B₀. The net B field in the interior of the solenoid may be expressed as 

B = B₀ + B_m 

where B_m is the field contributed by the material core. It turns out that this additional field B_m is proportional to the magnetisation M of the material and is expressed as 

Bm = μ₀M 

where μ0 is the same constant (permittivity of vacuum) that appears in Biot-Savart law. It is convenient to introduce another vector field H, called the magnetic intensity, which is defined by H = B/µ₀ - M 

where H has the same dimensions as M and is measured in units of Am^-1. Thus, the total magnetic field B is written as 

B = μ₀ (H + M) 

If we partition the contribution to the total magnetic field inside the sample into two parts: one, due to external factors such as the current in the solenoid. This is represented by H. The other is due to the specific nature of the magnetic material, namely M. The latter quantity can be influenced by external factors. This influence is mathematically expressed as 

M = χ H 

where χ, a dimensionless quantity, is appropriately called the magnetic susceptibility. It is a measure of how a magnetic material responds to an external field. lists χ for some elements. It is small and positive for materials, which are called paramagnetic. It is small and negative for materials, which are termed diamagnetic. In the latter case M and H are opposite in direction. we obtain, 

B = μ₀ (1 + χ H) = μ₀ μ_r H = μ H 

where μ_r = 1 + χ, is a dimensionless quantity called the relative magnetic permeability of the substance. It is the analog of the dielectric constant in electrostatics. The magnetic permeability of the substance is m and it has the same dimensions and units as μ₀; 

μ = μ₀ μ_r = μ₀ (1 + χ ) 

The three quantities χ, μ_r and μ are interrelated and only one of them is independent. Given one, the other two may be easily determined.  

Some of the commonly known ideas regarding magnetism are: 

(i) The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south to the geographic north. 

(ii) When a bar magnet is freely suspended, it points in the north-south direction. The tip which points to the geographic north is called the north pole and the tip which points to the geographic south is called the south pole of the magnet. 

(iii) There is a repulsive force when north poles (or south poles) of two magnets are brought close together. Conversely, there is an attractive force between the north pole of one magnet and the south pole of the other. 

(iv) We cannot isolate the north, or south pole of a magnet. If a bar magnet is broken into two halves, we get two similar bar magnets with somewhat weaker properties. Unlike electric charges, isolated magnetic north and south poles known as magnetic monopoles do not exist. 

(v) It is possible to make magnets out of iron and its alloys.