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प्रश्न
Answer the following question in detail.
How does the magnetic declination vary with latitude? Where is it minimum?
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उत्तर
Magnetic declination varies with location and over time. As one moves away from the true north the declination changes depending on the latitude as well as the longitude of the place. By convention, declination is positive when the magnetic north is east of true north, and negative when it is to the west. The decline is small in India. It is 0° 58′ west at Mumbai and 0° 41′ east at Delhi.
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संबंधित प्रश्न
Name three elements of the earth's magnetic field which help in defining earth's magnetic field completely.
The horizontal component of the earth’s magnetic field at a place is B and angle of dip is 60°. What is the value of vertical component of earth’s magnetic field at equator?
A magnetic needle, free to rotate in a vertical plane, orients itself vertically at a certain place on the Earth. What are the values of (i) Horizontal component of Earth’s magnetic field and (ii) angle of dip at this place?
Name the electromagnetic waves which (i) maintain the Earth’s warmth and (ii) are used in aircraft navigation.
A horizontal straight wire of length L extending from east to west is falling with speed v at right angles to the horizontal component of Earth’s magnetic field B.
(i) Write the expression for the instantaneous value of the e.m.f. induced in the wire.
(ii) What is the direction of the e.m.f.?
(iii) Which end of the wire is at the higher potential?
To keep valuable instruments away from the earth's magnetic field, they are enclosed in iron boxes. Explain.
What is a geographic meridian?
Answer the following question in detail.
Define the Angle of Dip.
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?
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?
The earth’s core is known to contain iron. Yet geologists do not regard this as a source of the earth’s magnetism. Why?
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?
A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at 22° with the horizontal. The horizontal component of the earth’s magnetic field at the place is known to be 0.35 G. Determine the magnitude of the earth’s magnetic field at the place.
A long straight horizontal cable carries a current of 2.5 A in the direction 10° south of west to 10° north of east. The magnetic meridian of the place happens to be 10° west of the geographic meridian. The earth’s magnetic field at the location is 0.33 G, and the angle of dip is zero. Locate the line of neutral points (ignore the thickness of the cable)? (At neutral points, magnetic field due to a current-carrying cable is equal and opposite to the horizontal component of earth’s magnetic field.)
Which of the following is responsible for the earth’s magnetic field?
Which of the following independent quantities is not used to specify the earth’s magnetic field?
At a given place on earth’s surface the horizontal component of earth’s magnetic field is 2 × 103-5 T and resultant magnetic field is 4 × 103-5 T. The angle of dip at this place is ______.
The small angle between magnetic axis and geographic axis at a place is ______.
Assertion(A): A magnetic needle free to rotate in a vertical plane, orients itself (with its axis) vertical at the poles of the earth.
Reason (R): At the poles of the earth the horizontal component of earth’s magnetic field will be zero.
Select the most appropriate answer from the options given below:
A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of the earth. Then,
A 10-meter wire is kept in east-west direction. It is falling down with a speed of 5.0 meter/second, perpendicular to the horizontal component of earth's magnetic field of 0.30 × 10−4 weber/meter2. The momentary potential difference induced between the ends of the wire will be:
The earth's magnetic field at a certain place has a horizontal component 0.3 gauss and the total strength 0.5 gauss. The angle of dip is ______.
Let the magnetic field on earth be modelled by that of a point magnetic dipole at the centre of earth. The angle of dip at a point on the geographical equator ______.
- is always zero.
- can be zero at specific points.
- can be positive or negative.
- is bounded.
The earth's magnetic field lines resemble that of a dipole at the centre of the earth. If the magnetic moment of this dipole is close to 8 × 1022 Am2, the value of earth's magnetic field near the equator is close to ______. (radius of the earth = 6.4 × 106 m)
