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Ashok0210

Asked: February 24, 2021In: Class 12 Physics

Answer the following questions: (a) The earth’s magnetic field varies from point to point in space. Does it also change with time? If so, on what time scale does it change appreciably? (b) The earth’s core is known to contain iron. Yet geologists do not regard this as a source of the earth’s magnetism. Why? (c) The charged currents in the outer conducting regions of the earth’s core are thought to be responsible for earth’s magnetism. What might be the ‘battery’ (i.e., the source of energy) to sustain these currents? (d) The earth may have even reversed the direction of its field several times during its history of 4 to 5 billion years. How can geologists know about the earth’s field in such distant past? (e) The earth’s field departs from its dipole shape substantially at large distances (greater than about 30,000 km). What agencies may be responsible for this distortion? (f) Interstellar space has an extremely weak magnetic field of the order of 10⁻¹² T. Can such a weak field be of any significant consequence? Explain. [Note: Exercise 5.2 is meant mainly to arouse your curiosity. Answers to some questions above are tentative or unknown. Brief answers wherever possible are given at the end. For details, you should consult a good text on geomagnetism.]

Class 12 Physics CBSE and UP Board Magnetism and Matter Chapter-5 Exercise 5.2 NCERT Solutions for Class 12 Physics Chapter 5 Question 2

Ashok0210

Asked: February 24, 2021In: Class 12 Physics

Answer the following questions regarding earth’s magnetism: (a) A vector needs three quantities for its specification. Name the three independent quantities conventionally used to specify the earth’s magnetic field. (b) The angle of dip at a location in southern India is about 18º. Would you expect a greater or smaller dip angle in Britain? (c) If you made a map of magnetic field lines at Melbourne in Australia, would the lines seem to go into the ground or come out of the ground? (d) In which direction would a compass free to move in the vertical plane point to, if located right on the geomagnetic north or south pole? (e) The earth’s field, it is claimed, roughly approximates the field due to a dipole of magnetic moment 8 × 10²² J T⁻¹ located at its centre. Check the order of magnitude of this number in some way. (f ) Geologists claim that besides the main magnetic N-S poles, there are several local poles on the earth’s surface oriented in different directions. How is such a thing possible at all?

Class 12 Physics CBSE and UP Board Magnetism and Matter Chapter-5 Exercise 5.1 NCERT Solutions for Class 12 Physics Chapter 5 Question 1

Ashok0210

Asked: February 24, 2021In: Class 12 Physics

The magnetic moment vectors µs and µl associated with the intrinsic spin angular momentum S and orbital angular momentum l, respectively, of an electron are predicted by quantum theory (and verified experimentally to a high accuracy) to be given by: µs = –(e/m) S, µl = –(e/2m)l Which of these relations is in accordance with the result expected classically? Outline the derivation of the classical result.

Class 12 Physics CBSE and UP Board Magnetism and Matter Chapter-5 Exercise 5.25 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 5 Question 25

Ashok0210

Asked: February 24, 2021In: Class 12 Physics

A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of 1.2 A?

Class 12 Physics CBSE and UP Board Magnetism and Matter Chapter-5 Exercise 5.24 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 5 Question 24

Ashok0210

Asked: February 24, 2021In: Class 12 Physics

A sample of paramagnetic salt contains 2.0 × 10²⁴ atomic dipoles each of dipole moment 1.5 × 10⁻²³ J T⁻¹. The sample is placed under a homogeneous magnetic field of 0.64 T, and cooled to a temperature of 4.2 K. The degree of magnetic saturation achieved is equal to 15%. What is the total dipole moment of the sample for a magnetic field of 0.98 T and a temperature of 2.8 K? (Assume Curie’s law

Class 12 Physics CBSE and UP Board Magnetism and Matter Chapter-5 Exercise 5.23 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 5 Question 23

A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of 1.2 A?

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