Which of the following is the correct representation of magnetic field lines?

1. (g), (c)

2. (d), (f)

3. (a), (b)

4. (c), (e)

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. T/2

3. 2/T                           

4. T

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:

Due to a small magnet, the intensity at a distance \(x\) in the end-on position is \(9~\text{gauss}\). What will be the intensity at a distance \(\frac{x}{2}\) on equatorial position?
1. \(9~\text{gauss}\)
2. \(4~\text{gauss}\)
3. \(36~\text{gauss}\)
4. \(4.5~\text{gauss}\)

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. $\frac{2{\mathrm{\mu }}_0\mathrm{M}}{4{\mathrm{\pi d}}^3}$

2. $\frac{{\mathrm{\mu }}_0\mathrm{M}}{4{\mathrm{\pi d}}^3}$

3. Zero

4. $\frac{\sqrt{5}{\mathrm{\mu }}_0\mathrm{M}}{4{\mathrm{\pi d}}^3}$

The unit of pole strength is:

1. $A{m}^2$

2. Am

3. $\frac{A^2}{m}$

4. $\frac{A^2}{m^2}$

Two similar bar magnets P and Q, each of magnetic moment M, are taken. If P is cut along its axial line and Q is cut along its equatorial line, all the four pieces obtained have:

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.

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 $\mu$T. When a horizontal field of 18 $\mu$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

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: