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Magnetism And Matter

Question
CBSEENPH12039522

Two short bar magnets of length 1 cm each have magnetic moments 1.20 Am2 and 1.00 Am2 respectively. They are placed on a horizontal table parallel to each other with their N poles pointing towards the South.
They have a common magnetic equator and are separated by a distance of 20.0 cm. The value of the resultant horizontal magnetic induction at the mid - point O of the line joining their centres is close to(Horizontal component of earth’s magnetic induction is 3.6 × 10–5 Wb/m2)

  • 3.6 x10-5 Wb/m2

  • 2.56 x10-4 Wb/m2

  • 3.50  x10-4 Wb/m2

  • 5.80 x  x10-4 Wb/m2

Solution

B.

2.56 x10-4 Wb/m2

straight B subscript net space equals space straight B subscript straight M subscript 1 end subscript space plus straight B subscript straight M subscript 2 end subscript plus straight B subscript straight H
space equals fraction numerator straight mu subscript 0 straight M subscript 1 over denominator 4 πx cubed end fraction space plus fraction numerator straight mu subscript 0 straight M subscript 2 over denominator 4 πx cubed end fraction space plus straight B subscript straight H
space equals space fraction numerator straight mu subscript straight o over denominator 4 πx cubed end fraction left parenthesis straight M subscript 1 plus straight M subscript 2 right parenthesis space plus space straight B subscript straight H
space equals 10 to the power of negative 7 end exponent over 10 to the power of negative 3 end exponent straight x 2.2 space plus 3.6 space straight X 10 to the power of negative 5 end exponent
equals 2.56 space straight X 10 to the power of negative 4 end exponent space Wb divided by straight m squared

Some More Questions From Magnetism and Matter Chapter

Answer the following question regarding earth:
 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?

Answer the following question regarding earth:
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?

Answer the following question regarding earth:
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?

Answer the following question:
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?

Answer the following question:
The earth's core is known to contain iron. Yet geologists do not regard this as a source of the earth's magnetism. Why?

Answer the following question:
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?

Answer the following question:
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?

Answer the following question:
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?