Plus Two Physics Chapter Wise Previous Questions Chapter 5 Magnetism and Matter

Plus Two Physics Chapter Wise Previous Questions Chapter 5 Magnetism and Matter is part of Kerala Plus Two Physics Chapter Wise Previous Questions and Answers Kerala. Here we have given Plus Two Physics Chapter Wise Questions and Answers Chapter 5 Magnetism and Matter.

Kerala Plus Two Physics Chapter Wise Previous Questions Chapter 5 Magnetism and Matter

Question 1.
How will you classify diamagnetic and paramagnetic materials based on magnetic susceptibilities? (March – 2009)
Answer:
Diamagnetic → Negative susceptibility
Paramagnetic → positive susceptibility

Question 2.
A magnetic needle made of iron is suspended in a uniform external magnetic field. It experiences a torque and the needle starts oscillating. (March – 2010)
a) Write down the frequency of oscillation of the magnetic needle.
b) If this magnetic needle is heated beyond curie temperature while it is oscillating, then its period.
a) increases
b) decreases
c) remains the same
d) becomes infinity
Answer:
a) Frequency

b) Increases.

When temperature increases ‘M’ decreases. Hence the period increases.

Question 3.
Magnetic materials are classified as diamagnetic, paramagnetic and ferromagnetic based on their properties. (Say – 2010)
a) Write one example each for diamagnetic and paramagnetic material.
b) If you place the above three magnetic substances between the pole pieces of a magnet, through which magnetic substance magnetic lines of force easily pass through and through which it passes least? Justify your answer.
Answer:
a) Diamagnet – Water, Copper, lead, bismath, NaCI Paramagnetic – Aluminium, Sodium, Calcium
b) Magnetic lines of force easily pass through Ferromagnetic substance. Because ferromagnetic substance has large positive value for permeability. Magnetic lines of force does not pass through diamagnetic substance because, the permeability is negative.

Question 4.
The captain of a ship sailing in the Atlantic Occean has to travel in the north direction to reach the nearest port. He finds that the magnetic declination of the present position of the ship is 5°22’ East. (March – 2011)
a) What is meant by magnetic declination?
b) The captain has a magnetic compass needle with him. By how much angle and in which direction should he deviate his ship from the north direction pointed by the magnetic compass needle to reach the port?
c) Suppose the magnetic needle is capable of rotating in a vertical plane about a horizontal axis. If the ship reaches the magnetic pole of the earth in which direction will the magnetic needle point?
Answer:

Declination at a place is the angle between the geographic meridian and magnetic meridian at that place.
b) 5°22’ west
c) upward direction or vertical direction.

Question 5.
When a magnetic needle is suspended by a string it comes to rest in the North-South direction. This shows that earth behaves as a magnet. (Say – 2011)
a) What is meant by magnetic elements of earth?
b) Definedipata place.
c) Obtain the relation  where H_E and Z_E are the components of earth’s magnetic field B_E along horizontal and vertical directions.
d) What happens if a magnetic needle is suspended at the magnetic poles?
Answer:
a) Declination, Dip and Horizontal component of earth’s magnetic field.
b) Dip at a place is the angle which the direction of total intensity of earth’s magnetic field makes with the horizontal.

d) The needle comes to rest in vertical direction.

Question 6.
Materials are classified into ferromagnetic, paramagnetic and diamagnetic according to their magnetic properties. (March – 2012)
a) Which one of the following is not ferromagnetic?
A) Cobalt
B) Iron
C) Nickel
D) Bismuth

b) Define the term magnetic susceptibility. What is its value for a perfect diamagnet?
c) State the reason why soft iron is used in making electromagnets.
Answer:
a) Bismuth
b) Magnetic susceptibility of a specimen is the ratio of its magnetization to the magnetising field.

Fordiamagnet, 1 < x < o
c) Soft iron is a ferromagnetic material. Electromagnets are usually ferromagnetic materials with low retentivity, low coercivity and high permeability. The hysteresis curve should be narrow so that the energy liberated as heat is small.

Question 7.
Earth behaves as a magnet with magnetic poles approximately near the geographic poles. (March – 2013)
a) The order of magnitude of earth’s magnetic field in tesla is …………….
b) What do you understand by ‘dynamo effect’?
c) Classify the following materials into diamagnetic and paramagnetic
i) Lead
ii) Magnesium
iii) Tungsten
iv) Copper
Answer:
a) 10^-6 Tesla
b) The earth’s core is very hot and molten. Circulating ions in the highly conducting liquid region of the earth’s core could form current loops and produce a magnetic field. This phenomenon is called dynamic effect.
c) Lead, copper → diamagnet
Magnesium, Tungsten → Paramagnet.

Question 8.
Materials are classified into diamagnetic, paramagnetic and ferromagnetic depending on their magnetic properties. (Say – 2013)
a) Which of the following is not diamagnetic?
i) Copper
ii) Water
iii) Aluminium
iv) Silicon

b) State and Explain Curie’s law.
Answer:
a) iii) Aluminium
b) Curie law of magnetism
Curie law of magnetism states that the magnetisation of a paramagnetic material is inversely proportional to the absolut temperature x. In the case of paramagnetic materials it can be shown that the magnetic susceptibility at temperature V is given by  Where C is a constant called curie constant.

Question 9.
Depending on the magnetic property, the materials are classified in to diamagnetic, paramagnetic and ferromagnetic. (March – 2014)
a) The behaviour of magnetic field lines near a magnetic substance is shown in the figure. Which material corresponds to the figure.

b) State and explain Curie’s law.
Answer:
a) Ferromagnetic material
b) Refer QuestionNo. 1 b Say 2013

Question 10.
Permanent magnets should have (March – 2015)
a) high retentivity and low coercivity.
b) low retentivity and high coercivity.
c) high retentivity and high coercivity.
d) low retentivity and low coercivity.
b. Distinguish between Para, Ferro and Diamagnetism.
Answer:
a) C
b) Diamagnetism : Diamagnetic substances are those which have tendency to move from stronger to the weaker part of the external magnetic field.

Paramagnetism : Paramagnetic substances are those which get weakly magnetized when placed in an external magnetic field. They have tendency to move from a region of weak magnetic field to strong magnetic field, i.e., they get weakly attracted to a magnet.

Ferromagnetism : Ferromagnetic substances are those which gets strongly magnetized when placed in an external magnetic field. They have strong tendency to move from a region of weak magnetic field to strong magnetic field, i.e., they get strongly attracted to a magnet.

Question 11.
Magnetic materials are broadly classified as diamagnetic, paramagnetic and ferromagnetic. (Say – 2016)
a) Mention the behaviour of dia and ferromagnetic materials when they are placed in a non-uniform magnetic field.
b) The temperature at which a ferromagnetic material becomes paramagnetic is
i) Transition temperature
ii) Critical temperature
iii) Curie temperature
iv) Triple point
Answer:
a)

b) Curie temperature

Question 12.
Explain hysteresis and draw a hysteresis curve for a ferromagnetic substance. (March – 2017)
Answer:
The induced magnetic field (B) lags behind the magnetising field (H). This is known as magnetic hysteresis.

Question 13.
a) The value of angle of dip at the magnetic poles of the earth is (Say – 2017)
i) zero
ii) 90°
iii) 30°
iv) 45°

b) A magnetic needle oscillates in a uniform magnetic field of strength B1 with a time period of 10 seconds. The same magnetic needle oscillates in another uniform magnetic field of strength B2 with a time period 20 seconds. Which magnetic field is strong, B₁ or B₂? Why?
Answer:
a) 90°
b) Period of oscillation

from this eq. (1), it is clear than B₁ > B₂

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