Which of the following is the correct representation of magnetic field lines?
1. | (g), (c) | 2. | (d), (f) |
3. | (a), (b) | 4. | (c), (e) |
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If a magnetic needle is made to vibrate in uniform field \(H\), then its time period is \(T\). If it vibrates in the field of intensity \(4H\), its time period will be:
1. | \(2T\) | 2. | \(\dfrac{T}{2}\) |
3. | \(\dfrac{2}{T}\) | 4. | \(T\) |
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A bar magnet of length \(l\) and magnetic dipole moment \(M\) is bent in the form of an arc as shown in the figure. The new magnetic dipole moment will be:
1. | \(\dfrac{3M}{\pi}\) | 2. | \(\dfrac{2M}{l\pi}\) |
3. | \(\dfrac{M}{ 2}\) | 4. | \(M\) |
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1. | \(9~\text{gauss}\) | 2. | \(4~\text{gauss}\) |
3. | \(36~\text{gauss}\) | 4. | \(4.5~\text{gauss}\) |
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Figure shows two small identical magnetic dipoles \(a\) and \(b\) of magnetic moments \(M\) each, placed at a separation \(2d\), with their axes perpendicular to each other. The magnetic field at the point \(P\) midway between the dipoles is:
1. | \(\dfrac{2 \mu_{0} M}{4 \pi d^{3}}\) | 2. | \(\dfrac{\mu_{0} M}{4 \pi d^{3}}\) |
3. | zero | 4. | \(\dfrac{\sqrt{5}\mu_{0} M}{4\pi d^{3}}\) |
The unit of pole strength is:
1. \(\text{Am}^2\)
2. \(\text{Am}\)
3. \(\frac{\text{A}^2}{\text{m}}\)
4. \(\frac{\text{A}^2}{\text{m}^2}\)
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1. | equal pole strength |
2. | magnetic moment \(\frac{M}{4}\) |
3. | magnetic moment \(\frac{M}{2}\) |
4. | magnetic moment \(M\) |
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Two equal bar magnets are kept as shown in the figure. The direction of the resultant magnetic field, indicated by arrowhead at the point \(P\) is: (approximately)
1. | 2. | ||
3. | 4. |
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A vibration magnetometer placed in a magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of 2 s in the earth's horizontal magnetic field of 24 T. When a horizontal field of 18 T is produced opposite to the earth's field by placing a current-carrying wire, the new time period of the magnet will be:
1. 1 s
2. 2 s
3. 3 s
4. 4 s
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Two identical bar magnets are fixed with their centres at a distance \(d\) apart. A stationary charge \(Q\) is placed at \(P\) in between the gap of the two magnets at a distance \(D\) from the centre \(O\) as shown in the figure.
The force on the charge \(Q\) is:
1. | zero. |
2. | directed along with \(OP\). |
3. | directed along with \(PO\). |
4. | directed perpendicular to the plane of the paper. |
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