Write examples for diamagnetic substances, paramagnetic substances and ferromagnetic substances.

define

1. diamagnetism,
2. paramagnetism,
3. ferromagnetism

state curie’s law

Susceptibility is slightly positive for

a. diamagnetic substances

b. paramagnetic substances

c. ferromagnetic substances

which of the following directions at earths magnetic pole will a compass needle show?

a. Vertical

b. no direction

c. horizontal

d. inclined 45^o to vertical

The vertical component of earths magnetic field is zero at a place where the angle of dip is __________

a.0⁰

b.45⁰

c.60⁰

d.90⁰

The dipole moment of a short bar magnet is 1.25 Am². Find the magnetic field on the axis at a distance 0.5 metre from the centre of the magnet.

A steel wire of length 2l has a magnetic moment M. It is bend into a semicircular arc. What is the new magnetic moment?

If the distance between two similar magnetic poles held 1 centimetre apart be doubled, then the force of interaction between them will be:

1. doubled
2. halved
3. unchanged
4. one quarter of the original value.

1. A bar magnet of length 2l, magnetic moment M and pole strength m units is cut into two pieces at the middle. The magnetic moment and pole strength of each piece will be respectively:

   1. M/2 and m/2

   2. M and m/2

   3. M/2 and m

   4. M and m

when the distance between two magnetic poles is doubled the force between them is

1. doubled
2. halved
3. increased 4 times
4. decreased 4 times

The magnetic moment of a short magnet is 16 Am². What is the field strength at apoint 20 cm from its mid point on

(a). Axial line (b). equatorial line.

Of the following the most suitable material for making permanent magnet?

1. Steel
2. soft iron
3. copper
4. Nickel

What are the quantities we need to describe the magnetic field of the earth at a point on its surface?

What is dip or inclination?

What is magnetic declination?

What is dynamo effect?

How can you determine which material is suitable for making permanent magnet?

Why the magnetic field lines can't represent the lines of force on a moving charged particle at every point?

state Gauss’s law in magnetism

The magnetic needle has magnetic moment 6.7 × 10^–2 Am² and moment of inertia I = 7.5 × 10 ^–6 kg m². It performs 10 complete oscillations in 6.70 s. What is the magnitude of the magnetic field?

The tangent to the magnetic field line at a given point represents _______________

How can you determine which material is suitable for making temporary magnet?

When a magnetic needle is placed in a non-uniform magnetic field it experiences

i) a force but no torque ii) a torque but no force iii) Force and torque iv) neither a force nor a torque.

a. Identify the labels, A, B, C.     

b. The lines drawn on a map through places that have the same declination are called.........     

c. The horizontal component of earth’s magnetic field at a place is 0.25×10^-4 T and the resultant magnetic field is 0.5×10^-4 T. Find the dip and the vertical component of the earth’s magnetic field at the place.     

The temperature at which a ferromagnetic material became paramagnetic is ........

Materials are classified into ferromagnetic, paramagnetic and diamagnetic according to their magnetic properties.

a. which one of the following is not a ferromagnetic material?

i. Cobalt

ii. iron

iii. Nickel

iv. Bismuth

b. define the term magnetic susceptibility.

c. What is its value for a perfect diamagnetic substance.

d. State the reason why soft iron is used in making electromagnets.

Earth behaves as a magnet with magnetic poles approximately near the geographic poles.

a. The order of magnitude of Earth's magnetic field in Tesla is ..............

b. what do you understand by ‘dynamo’ effect?

a. State Gauss's Law in magnetism

b. how this differ from Gauss's Law in electrostatics

c. what is the difference in two cases

A magnetic needle made of iron is suspended in a uniform external magnetic field it experiences a torque and the needle starts oscillating.

a. Write down the frequency of oscillation of the magnetic needle

b. if the needle is heated beyond Curie temperature while it is oscillating then its period

i. increases ii. decreases iii. remains the same iv. becomes infinity

Why a freely suspended or pivoted magnetic needle always comes to rest along the geographical N – S direction.

Why diamagnetism is almost independent of temperature?

Write the formula for torque on a magnetic dipole in an external magnetic field. Also write conditions for maximum and minimum torque.

A magnet can be cut in two ways, perpendicular to its axis and parallel to its axis. In these two ways what are the changes occur in pole strength?

State directive property of a magnet.

Why does a paramagnetic sample display greater magnetisation when cooled?

The earth’s magnetic field varies from point to point in space, does its also changes with time? Explain

SI unit of magnetic moment is..............

 Identify the magnetic substances ‘a’ and ‘b’.

Super conductor belongs to which type of magnetic material ( Para magnetic / dia magnetic / ferro magnetic)

what happens if an iron bar magnet is heated to very high temperature

The earth core is known to contain iron . Yet geologist do not regarded this as the source of Earth's magnetism why?

An iron nail near a bar magnet experiences a force of attraction in addition to a torque. Why?

Do the magnetic field lines also represent the lines of force on a moving charged particle at every point?

Is a magnetised needle in a uniform magnetic field experiences a force?.

A magnetised needle in a uniform magnetic field experiences ...................

Name the physical quantity whose SI unit is weber

Simplest example of magnetic dipole is .........