magnetism

1.) The property of following magnetic lines of force through material is
A)	relative permeability
B)	permeability
C)	intensity of magnetisation
D)	susceptibility
2.) The magnetic length of a bar magnet is 10cm. Its geometric length is
A)	10 cm
B)	12 cm
C)	5 cm
D)	6 cm
3.) Screens to prevent the magnetic effects are made of
A)	Glass
B)	Wood
C)	Iron
D)	Brass
4.) A bar magnet of magnetic moment 5A-m2 has poles 20 cm apart its pole strength si
A)	50 A-m
B)	15 A-m
C)	25 A-m
D)	45 A-m
5.) In working with deflection magnetometer, the proportional error will be minimum when the deflection is
A)	o‘>30o
B)	o‘>45o
C)	o‘>60o
D)	o‘>90o
6.) A magnetised wire of moment 1.57 Am2 is bent in the form of a semicircle. The new magnetic moment will be
A)	2‘>0.1 Am2
B)	2‘>10 Am2
C)	2‘>1 Am2
D)	2‘>110 Am2
7.) Two small magnet produces no deflection when placed at 10cm and 20cm respectively on the two arms of a deflection magnetometer. The ratio of their magnetic moments is
A)	1:4
B)	1:8
C)	8:1
D)	4:1
8.) The ratio of magnetic inductions at distances r1 and r2 from a magnetic pole is___
A)	1 : r2‘>r1 : r2
B)	2 : r1‘>r2 : r1
C)	22 : r21‘>r22 : r21
D)	1 : 1
9.) The time period of a magnet at a place of magnetic field 4B is T. Time period at a place where magnetic field is B is
A)	2T
B)	3T
C)	4T
D)	16T
10.) Which of the following is best for permanent magnets is
A)	alnico
B)	iron
C)	steel
D)	Brass
11.) A magnetic field is produced and directed along y-axis. A magnet is placed along x-axis. The direction of torque on the magnet is
A)	in the x-y plane
B)	along y-axis
C)	along z-axis
D)	Torque will be zero
12.) The best method for demagnetisation is
A)	Dropping the magnet from some height
B)	Hammering the magnet
C)	Heating the magnet
D)	Sending alternating currents through the magnet
13.) Deflection magnetometer works on
A)	Coulomb’s law
B)	Curie law
C)	Tangent law
D)	The law of vibration of a magnet
14.) Find out the wrong statement
A)	The lines of force may intersect
B)	The lines of force never intersect
C)	The tangent drawn to the line of induction at any point gives the direction of magnetic induction at that point.
D)	None
15.) Vibration magnetometer works on the principle of
A)	Torque acting an the bar magnet
B)	Force acting on the bar magnet
C)	Both the force and the torque acting on the bar magnet
D)	None of the above
16.) The ratio of intensities of magnetic fields due to a short magnet in tan A and tan B position at the same distance is
A)	1:2
B)	2:1
C)	2:3
D)	1:4
17.) The acceleration aquired by the pole in the above problem is___
A)	2‘>2 m/s2
B)	2‘>20 m/s2
C)	2‘>4 m/s2
D)	2‘>40 m/s2
18.) Two magnets have their length in the ratio 2:3 and their pole strengths in the ratio 3:4. the ratio of their magnetic moment is
A)	2:1
B)	4:1
C)	1:2
D)	1:4
19.) The distance at which resultant induction becomes zero on the line joining the poles in the above problem is
A)	doesn’t form
B)	5cm
C)	10cm
D)	15cm
20.) In the above problem, The distance of each pole from the nearest end is
A)	2 cm
B)	4 cm
C)	1 cm
D)	5 cm
21.) Magnetic induction at a point in air at a distance 6cm away from a pole of strength 9 A-m is
A)	-3 T’>2.5 x 10-3 T
B)	-2 T’>2.5 x 10-2 T
C)	-5 T’>2.5 x 10-5 T
D)	-4 T’>2.5 x 10-4 T
22.) Two points A and B are located at equal distances from the centre of the short magnet on the axial line and equitorial line. The ratio of inductions at A and B is
A)	1:1
B)	2:1
C)	1:2
D)	4:1
23.) Two magnetic poles of strength 2 A-m each are separated by 10cm in air. The force between them is
A)	-5 N’>0.4 x 10-5 N
B)	-5 N’>0.04 x 10-5 N
C)	-5 N’>4 x 10-5 N
D)	-5 N’>40 x 10-5 N
24.) The time periods of a magnet in two fields are 1s and 4s, compare the two fields.
A)	4:1
B)	16:1
C)	1:16
D)	1:4
25.) The moments of inertia as well as the time periods of two magnets are in the ratio of 1:2. The ratio of their magnetic moments is
A)	2:1
B)	1:2
C)	4:3
D)	3:4