10 Question-Answer on Magnetism of earth
1. The needle of a dip circle when placed at a geomagnetic pole stays along
(a) South north direction only
(b) East west direction only
(c) Vertical direction
(d) None of above
Ans: ( c)
2. The lines of force due to earth’s horizontal magnetic field are:
(a) Parallel, straight and horizontal
(b) Concentric circle
(c) Elliptical
(d) Curved lines.
Ans: (a)
3. The vertical component of earth’s magnetic field is zero at;
(a) Magnetic equator
(b) Magnetic pole
(c) Geographic pole
(d) At 90˚ latitude
Ans: (a)
4. A dip needle which is free to move in a vertical plane perpendicular to magnetic meridian will remain
(a) Horizontal
(b) Vertical
(c) Neither horizontal nor vertical
Ans : ( b)
5. The arms of a deflection magnetometer in the tangent B position are placed along
(a) The east west direction
(b) The north south direction
(c) The north east—south west direction
(d) The north west-south east direction
Ans: (b)
6. The point at which two or more magnetic fields cancel each other is called
(a) Focal point
(b) Inversion point
(c) Neutral point
(d) None of above
Ans: ( c)
7. A deflection magnetometer can be used for measuring
(a) Declination
(b) Dip
(c) Horizontal component
(d) All these
Ans: (c)
8. A mariner’s compass shows
(a) Geographic NS direction
(b) Magnetic NS direction
(c) Both ‘a’ and ‘b’
(d) None of these
Ans: ( b)
9. A permanent magnet
(a) Attracts all substance
(b) Attracts only ferromagnetic substances
(c) Attracts ferromagnetic substances and repels all others
(d) Attracts some substances and repels others.
Ans: (d)
10. The magnetizing field required to be applied in opposite direction to reduce residual magnetism to zero is called:
(a) Coercivity
(b) Retentivity
(c) Hysteresis
(d) None of the above
Ans: ( a)