An iron sample having mass 8 . 4 kg is repeatedly taken over cycles of magnitisation and demagnetisation at a frequency of 50 cycles s - 1 . It is found that 3 . 2 × 10 4 J of energy is dissipated as heat in the sample in 30 minutes. Find the energy dissipated per unit volume per cycle in the iron sample. Density of iron = 7200 kg m - 3 .

Here W = 3 . 2 × 10 4 J , v = 50 cycle s - 1 , t = 30 min = 1800 s Volume, V = Mass Density = 8 .4 7200 kg m − 3 Energy dissipated per unit volume per cycle, Q = W V × v × t = 3 .2 × 10 4 × 7200 8 .4 × 50 × 1800 = 304 .8 Jm − 3 cycle − 1

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Two magnets of magnetic moments $m$ and $3 m$ are mounted so as to cross each other at an angle of $60 °$ . The combination rests horizontally when suspended by a silk fibre. Fins the angle which the weaker magnet makes with the magnetic meridian.

Important Questions on Magnetism

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12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>HOTS Problem on Higher Order Thinking Skills>Q 20

An iron sample having mass

8.4 kg

is repeatedly taken over cycles of magnitisation and demagnetisation at a frequency of

50

cycles

s^{- 1}

. It is found that

3.2 \times 10^{4} J

of energy is dissipated as heat in the sample in

30

minutes. Find the energy dissipated per unit volume per cycle in the iron sample. Density of iron

= 7200 kg m^{- 3}

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12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>HOTS Problem on Higher Order Thinking Skills>Q 21

Find Curie constant for chromium potassium alum from its $x$ vs. $1 / T$ graph shown in figure below.

Question Image

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New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>HOTS Problem on Higher Order Thinking Skills>Q 22

A magnetic dipole is placed in a uniform magnetic field with its axis tilted with respect to its position of stable equilibrium. Deduce an expression for the time period of (small amplitude) oscillation of this magnetic dipole about an axis, passing through its centre and perpendicular to its plane.

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New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>HOTS Problem on Higher Order Thinking Skills>Q 22

If this bar magnet is replaced by a combination of two similar bar magnets, placed over each other, how will the time period vary?

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12th CBSE

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New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>GUIDELINES TO NCERT EXERCISES>Q 5.1.

Answer the following question regarding earth’s magnetism:
A vector needs three quantities for its specification. Name the three independent quantities conventionally used to specify the earth’s magnetic field.

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12th CBSE

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New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>GUIDELINES TO NCERT EXERCISES>Q 5.1.

Answer the following question regarding earth’s magnetism: The angle of dip at a location in southern India is about

18 °

. Would you expect a greater or smaller dip angle in Britain?

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12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>GUIDELINES TO NCERT EXERCISES>Q 5.1.

Answer the following question regarding earth’s magnetism:

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?

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12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>GUIDELINES TO NCERT EXERCISES>Q 5.1.

Answer the following question regarding earth’s magnetism:
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?

Two magnets of magnetic moments m and 3 m are mounted so as to cross each other at an angle of 60°. The combination rests horizontally when suspended by a silk fibre. Fins the angle which the weaker magnet makes with the magnetic meridian.

Important Questions on Magnetism

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Two magnets of magnetic moments $m$ and $3 m$ are mounted so as to cross each other at an angle of $60 °$ . The combination rests horizontally when suspended by a silk fibre. Fins the angle which the weaker magnet makes with the magnetic meridian.