QBManager

PHXII05:MAGNETISM and MATTER

360618 An iron rod of length $L$ and magnetic moment $M$ is bent in the form of a semicircle. Now its magnetic moment will be

1

M π

2

\frac{2 M}{π}

3

M

4

\frac{M}{π}

Explanation:

On bending a rod its pole strength remains unchanged whereas its magnetic moment changes.
New magnetic moment
$M^{'} = m (2 R) = m (\frac{2 l}{π}) = (\frac{2 M}{π})$

PHXII05:MAGNETISM and MATTER

360619 A bar magnet of length $l$ and magnetic dipole moment $M$ is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be
supporting img

1

\frac{M}{2}

2

\frac{2}{π} M

3

\frac{3}{π} M

4

M

Explanation:

The magnetic moment,
$M = m l (\begin{array}{l} m = pole strength \\ l = length of magnet \end{array})$
According to question,
$l = \frac{π}{3} \times r$
So, $r = \frac{3 l}{π}$
New magnetic moment, $M^{'} = m \times (2 r \sin 30^{\circ})$
$= m \times \frac{3 l}{π} = \frac{3}{π} \cdot m l$ $= \frac{3 M}{π}$

PHXII05:MAGNETISM and MATTER

360620 A magnet of magnetic moment $M$ and pole strength $m$ is divided in two equal parts, the magnetic moment of each part will be

1 2

M

2

M / 2

3

M

4

\sqrt{2} M

Explanation:

If magnet cuts parallel to length then pole strength becomes half and length will be the same
$M^{'} = (\frac{m}{2}) 2 l = M / 2$
If it cuts parallel to equatorial line than pole strength is same but length becomes half
$M^{'} = (m) \frac{2 l}{2} = \frac{M}{2}$

PHXII05:MAGNETISM and MATTER

360621 The dimensional formula for magnetic moment is

1

M^{0} L^{2} T^{0} A^{1}

2

M^{0} L^{1} T^{0} A^{2}

3

M^{0} L^{2} T^{0} A^{2}

4

M^{0} L^{0} T^{1} A^{1}

Explanation:

Magnetic moment $= m (2 l)$
$= (A m) m = A m^{2} = M^{\circ} L^{2} T^{\circ} A$

PHXII05:MAGNETISM and MATTER

360618 An iron rod of length $L$ and magnetic moment $M$ is bent in the form of a semicircle. Now its magnetic moment will be

1

M π

2

\frac{2 M}{π}

3

M

4

\frac{M}{π}

Explanation:

On bending a rod its pole strength remains unchanged whereas its magnetic moment changes.
New magnetic moment
$M^{'} = m (2 R) = m (\frac{2 l}{π}) = (\frac{2 M}{π})$

PHXII05:MAGNETISM and MATTER

360619 A bar magnet of length $l$ and magnetic dipole moment $M$ is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be
supporting img

1

\frac{M}{2}

2

\frac{2}{π} M

3

\frac{3}{π} M

4

M

Explanation:

The magnetic moment,
$M = m l (\begin{array}{l} m = pole strength \\ l = length of magnet \end{array})$
According to question,
$l = \frac{π}{3} \times r$
So, $r = \frac{3 l}{π}$
New magnetic moment, $M^{'} = m \times (2 r \sin 30^{\circ})$
$= m \times \frac{3 l}{π} = \frac{3}{π} \cdot m l$ $= \frac{3 M}{π}$

PHXII05:MAGNETISM and MATTER

360620 A magnet of magnetic moment $M$ and pole strength $m$ is divided in two equal parts, the magnetic moment of each part will be

1 2

M

2

M / 2

3

M

4

\sqrt{2} M

Explanation:

If magnet cuts parallel to length then pole strength becomes half and length will be the same
$M^{'} = (\frac{m}{2}) 2 l = M / 2$
If it cuts parallel to equatorial line than pole strength is same but length becomes half
$M^{'} = (m) \frac{2 l}{2} = \frac{M}{2}$

PHXII05:MAGNETISM and MATTER

360621 The dimensional formula for magnetic moment is

1

M^{0} L^{2} T^{0} A^{1}

2

M^{0} L^{1} T^{0} A^{2}

3

M^{0} L^{2} T^{0} A^{2}

4

M^{0} L^{0} T^{1} A^{1}

Explanation:

Magnetic moment $= m (2 l)$
$= (A m) m = A m^{2} = M^{\circ} L^{2} T^{\circ} A$

PHXII05:MAGNETISM and MATTER

360618 An iron rod of length $L$ and magnetic moment $M$ is bent in the form of a semicircle. Now its magnetic moment will be

1

M π

2

\frac{2 M}{π}

3

M

4

\frac{M}{π}

Explanation:

On bending a rod its pole strength remains unchanged whereas its magnetic moment changes.
New magnetic moment
$M^{'} = m (2 R) = m (\frac{2 l}{π}) = (\frac{2 M}{π})$

PHXII05:MAGNETISM and MATTER

360619 A bar magnet of length $l$ and magnetic dipole moment $M$ is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be
supporting img

1

\frac{M}{2}

2

\frac{2}{π} M

3

\frac{3}{π} M

4

M

Explanation:

The magnetic moment,
$M = m l (\begin{array}{l} m = pole strength \\ l = length of magnet \end{array})$
According to question,
$l = \frac{π}{3} \times r$
So, $r = \frac{3 l}{π}$
New magnetic moment, $M^{'} = m \times (2 r \sin 30^{\circ})$
$= m \times \frac{3 l}{π} = \frac{3}{π} \cdot m l$ $= \frac{3 M}{π}$

PHXII05:MAGNETISM and MATTER

360620 A magnet of magnetic moment $M$ and pole strength $m$ is divided in two equal parts, the magnetic moment of each part will be

1 2

M

2

M / 2

3

M

4

\sqrt{2} M

Explanation:

If magnet cuts parallel to length then pole strength becomes half and length will be the same
$M^{'} = (\frac{m}{2}) 2 l = M / 2$
If it cuts parallel to equatorial line than pole strength is same but length becomes half
$M^{'} = (m) \frac{2 l}{2} = \frac{M}{2}$

PHXII05:MAGNETISM and MATTER

360621 The dimensional formula for magnetic moment is

1

M^{0} L^{2} T^{0} A^{1}

2

M^{0} L^{1} T^{0} A^{2}

3

M^{0} L^{2} T^{0} A^{2}

4

M^{0} L^{0} T^{1} A^{1}

Explanation:

Magnetic moment $= m (2 l)$
$= (A m) m = A m^{2} = M^{\circ} L^{2} T^{\circ} A$

PHXII05:MAGNETISM and MATTER

360618 An iron rod of length $L$ and magnetic moment $M$ is bent in the form of a semicircle. Now its magnetic moment will be

1

M π

2

\frac{2 M}{π}

3

M

4

\frac{M}{π}

Explanation:

On bending a rod its pole strength remains unchanged whereas its magnetic moment changes.
New magnetic moment
$M^{'} = m (2 R) = m (\frac{2 l}{π}) = (\frac{2 M}{π})$

PHXII05:MAGNETISM and MATTER

360619 A bar magnet of length $l$ and magnetic dipole moment $M$ is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be
supporting img

1

\frac{M}{2}

2

\frac{2}{π} M

3

\frac{3}{π} M

4

M

Explanation:

The magnetic moment,
$M = m l (\begin{array}{l} m = pole strength \\ l = length of magnet \end{array})$
According to question,
$l = \frac{π}{3} \times r$
So, $r = \frac{3 l}{π}$
New magnetic moment, $M^{'} = m \times (2 r \sin 30^{\circ})$
$= m \times \frac{3 l}{π} = \frac{3}{π} \cdot m l$ $= \frac{3 M}{π}$

PHXII05:MAGNETISM and MATTER

360620 A magnet of magnetic moment $M$ and pole strength $m$ is divided in two equal parts, the magnetic moment of each part will be

1 2

M

2

M / 2

3

M

4

\sqrt{2} M

Explanation:

If magnet cuts parallel to length then pole strength becomes half and length will be the same
$M^{'} = (\frac{m}{2}) 2 l = M / 2$
If it cuts parallel to equatorial line than pole strength is same but length becomes half
$M^{'} = (m) \frac{2 l}{2} = \frac{M}{2}$

PHXII05:MAGNETISM and MATTER

360621 The dimensional formula for magnetic moment is

1

M^{0} L^{2} T^{0} A^{1}

2

M^{0} L^{1} T^{0} A^{2}

3

M^{0} L^{2} T^{0} A^{2}

4

M^{0} L^{0} T^{1} A^{1}

Explanation:

Magnetic moment $= m (2 l)$
$= (A m) m = A m^{2} = M^{\circ} L^{2} T^{\circ} A$