Question
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Answer
- (b) $\frac{\pi}{3}$
Explanation:
$\tan\theta=\frac{\text{B}_\text{V}}{\text{B}_\text{H}}$ and $\text{B}_\text{H}=\frac{\text{B}_\text{V}}{\sqrt{3}}$
$\therefore\tan\theta=\sqrt{3}\text{ i.e. }\theta=\frac{\pi}{3}$
- (b) Magnetic declination.
Explanation:
The angle between the true geographic north and the north shown by a compass needle is called as magnetic declination or simply declination.
- (d) 90º, 0º
Explanation:
Since angle of dip at a place is defined as the angle $\delta,$ which is the direction of total intensity of earth's magnetic field B makes with a horizontal tine in magnetic meridian,
At poles $\text{B}=\text{B}_\text{V}$ and $\text{B}_\text{V}=\text{B}\sin\delta\therefore\sin\delta=1\Rightarrow\delta=90^\circ$
At equator $\text{B}=\text{B}_\text{H}$ and $\text{B}_\text{H}=\text{B}\cos\delta$
$\therefore\cos\delta=1\Rightarrow\delta=-0^\circ.$
- (a) Will become rigid showing no movement.
Explanation:
A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It will stay in any position as the horizontal component of earth's magnetic field becomes zero at the geomagnetic pole.
- (c) Magnetic dip increases as we move away from the equator towards the magnetic pole.
Explanation:
At equator, $\delta=0^\circ$
At poles, $\delta=90^\circ$
$\therefore\delta$ increases as we move from equator towards poles.
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