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The pole of the magnet that points towards north is called its north pole the other pole which points towards south is called its south seeking pole or south pole.

(b) at the two ends

A magnet has poles two

1. North, South 

2. artificial magnet 

3. iron 

4. repulsion

(c) to lift heavy objects made of iron

1. A freely suspended magnet always comes to rest in the north south direction.

2. Magnets only attract magnetic materials.

3. There is attraction between unlike poles of magnet and repulsion between like poles of magnet.

1. Bar magnets should be kept in pairs with their unlike poles on the same side.

2. Bar magnets must be separated by a piece of wood while two pieces of soft iron should be placed across their ends.

3. Apiece of iron should be kept across the poles of a horse shoe magnet.

4. Magnets should not be heated, hammered or dropped from some height as they will lose their properties by these activities.

1. Magnetic substances : Those substances which attract towards the magnet, are called magnetic substances.

Example : iron, cobalt, nickel. 

2. Non Magnetic substances : They are not attracted towards magnet.

Example : Plastic, glass, wood, leather etc.

Correct answer is (a) i ∝  θ

Given: Cross-sectional area A = 1 cm²
Magnetising field H = 200 oersted
Produced magnetic field B = 3000G
Permeability μ = \(\frac{B}{H}=\frac{3000}{200}\) = 15
and μ = (1 + X_m
15 = (1 + X_m)
Magnetic susceptibility X_m = 15 - 1 = 14

It is not advisable to slide a magnet on an iron bar back and forth because moving it in opposite directions will work to cancel each other out.

Correct option is: (A) 90°

i. At the poles, earth’s magnetic field is exactly vertical. As the compass needle is free to rotate in a horizontal plane only, it may point out in any direction.

ii. The earth’s magnetic field is only approximately a dipole field. Hence the local N-S poles may lie oriented in different directions. This is possible due to deposits of magnetised minerals in the earth’s crust.

Diamagnetic substance. Because for diamagnetic substance, magnetic susceptibility is negative and always less than.

(b) paramagnetic
As μ_r > 1, so substance should be paramagnetic.

(c) diamagnetic substances
For diamagnetic substances.

Pieces of iron or other materials are made magnets by rubbing them with natural magnets (or by passing direct current through a wire wound around them). This is how artificial magnets are made.

Natural magnets: Natural magnets are those which are found in nature e.g. load stone.

Artificial magnets: Man made magnets are called artificial magnets, e.g. electromagnet.

Magnetic substances: The substances that get attracted by a magnet are called magnetic substances. Iron, steel, cobalt and nickel are magnetic substance

Non-magnetic substances : The substances that do not get attracted by a magnet are called non-magnetic substances, e.g., wood, plastic, copper, paper, aluminum, rubber, stone.

Examples of magnetic substances – Iron, nickel, cobalt

Examples of non-magnetic substances – Plastic, wool, wood, paper, rubber, etc.

A magnet is a piece of metal that can attract metals such as iron cobalt and nickel. Naturally occurring rocks such as Lodestone or magnetite have the ability of attracting magnetic substances and hence are called natural magnets. Magnets that are made by man from magnetic substances ara called artificial magnets. These come in different shapes such as bar magnets, horse shoe magnets, disc magnets and ring magnets. Artificial magnets can be made in any size, shape or strength as desired but natural magnets cannot be made as desired.

(a)False

Artificial magnets are stronger than the natural magnets.

(b) True

(c)True

(d) False.

A magnet get demagnetised when it is heated to a very high temperature.

(e) False.

Permanent magnets cannot be demagnetised.

(f) True

(g) False.

Electrical method is better than single touch method.

(h) False.

Magnetic keepers are the pieces of soft iron.

(i) True

Magnets must be handled with care or else they lose their magnetic properties and become weak. To prevent a magnet from becoming demagnetized, magnet should not be handled roughly, hammered, dropped, heated. It should be stored using magnetic keepers.

Earths magnetism is due to electrical currents produced by the convective motion of mainly molten iron and nickel in the outer core of the earth.  

The net magnetic flux through any closed surface is zero. 

Consider a small vector area element ∆s of closed surface S. According to Gauss law in magnetism, net flux though closed surface, ∅B= B .∆s all area element = 0. 

The implication of Gauss law is that isolated magnetic poles do not exist.