Solenoid and Bar Magnet

Q. A current loop placed in a magnetic field behaves like a

1. Magnetic substance
2. Magnetic pole
3. All are true
4. Magnetic dipole

Q. The magnetic field lines due to a bar magnet are correctly shown in

1. 
2. 
3. 
4. 

Q. The magnetic lines of force inside a bar magnet

1. Are from north-pole to south-pole of the magnet
2. Do not exist
3. Are from south-pole to north-pole of the magnet
4. Depend upon the area of cross-section of the bar magnet

Q. Two identical short bar magnets, each having magnetic moment of $10A{m}^2$, are arranged such that their axial lines are perpendicular to each other and their centres be along the same straight line in a horizontal plane. If the distance between their centres is 0.2 m, the resultant magnetic induction at a point midway between them is $({\mu }_0=4\pi \times {10}^{-7}H{m}^{-1})$

1. $\sqrt{2}\times {10}^{-7}$ Tesla
2. $\sqrt{5}\times {10}^{-7}$ Tesla
3. $\sqrt{2}\times {10}^{-3}$ Tesla
4. $\sqrt{5}\times {10}^{-3}$ Tesla

Q. The ultimate individual unit of magnetism in any magnet is called

1. South pole
2. Dipole
3. Quadrupole
4. North pole

Q. 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

1. Magnetic moment $\frac{M}{4}$
2. Magnetic moment $\frac{M}{2}$
3. Equal pole strength
4. Magnetic moment M

Q. A bar magnet of length 3 cm has points A and B along its axis at distances of 24 cm and 48 cm on the opposite sides. Ratio of magnetic fields at these points will be

1. $4$
2. $\frac{1}{2\sqrt{2}}$
3. 8
4. $3$

Q. A small bar magnet has a magnetic moment $1.2A-m^2$. The magnetic field at a distance 0.1 m on its axis will be: $({\mu }_0=4\pi \times {10}^{-7}T-m/A)$

1. $1.2\times {10}^{-4}T$
2. $2.4\times {10}^{-4}T$
3. $2.4\times {10}^{4}T$
4. $1.2\times {10}^{4}T$

Q. Points A and B are situated along the extended axis of 2 cm long bar magnet at a distance x and 2x cm respectively. From the pole nearer to the points, the ratio of the magnetic field at A and B will be

1. 4 : 1 exactly
2. 4 : 1 approx
3. 8 : 1 exactly
4. 8 : 1 approx

Q. The magnetism of magnet is due to

1. Earth
2. The spin motion of electron
3. Pressure of big magnet inside the earth
4. Cosmic rays