Neutral Point Near a Magnet, Deflection Magnetometer (Board Level)

1.

Magnetic moments of two bar magnets may be compared with the help of 

(a) Deflection magnetometer

(b)  Vibration magnetometer

(c)  Both of the above

(d)  None of the above

Ans (c)

2.

The time period of oscillation of a freely suspended bar magnet with usual notations is given by

(a)      T=2\pi \sqrt{{\frac{I}{{M{{B}_{H}}}}}}         

(b)     T=2\pi \sqrt{{\frac{{M{{B}_{H}}}}{I}}}

(c)      T=\sqrt{{\frac{I}{{M{{B}_{H}}}}}}    

(d)     T=2\pi \sqrt{{\frac{{{{B}_{H}}}}{{MI}}}}

Ans (a)

3.

In sum and difference method in vibration magnetometer, the time period is more if

 (a) Similar poles of both magnets are on same sides

(b)  Opposite poles of both magnets are on same sides

(c)  Both magnets are perpendicular to each other

(d)  Nothing can be said

Ans (b)

4.

Vibration magnetometer before use, should be set

(a)  In magnetic meridian

(b)  In geographical meridian

(c)  Perpendicular to magnetic meridian

(d)  In any position

Ans (a)

5.

Magnets A and B are geometrically similar but the magnetic moment of A is twice that of B. If T₁ and T₂ be the time periods of the oscillation when their like poles and unlike poles are kept together respectively, then \frac{{{{T}_{1}}}}{{{{T}_{2}}}}will be

(a)  \frac{1}{3}                                         

(b)  \frac{1}{2}

(c)  \frac{1}{{\sqrt{3}}}                        

(d) \sqrt{3}

Ans  (c)

6.

Vibration magnetometer works on the principle of

(a)  Torque acting on 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 these

Ans (a)

7.

Tangent galvanometer is used to measure

(a)  Steady currents

(b)  Current impulses

(c)  Magnetic moments of bar magnets

(d)  Earth’s magnetic field

Ans (a)

8.

The sensitivity of a tangent galvanometer is increased if

 (a) Number of turn decreases

(b)  Number of turn increases

(c)  Field increases             

(d)  None of the above

Ans (b)

9.

The period of oscillations of a magnetic needle in a magnetic field is 1.0 sec. If the length of the needle is halved by cutting it, the time period will be

(a)  1.0 sec                             

(b)  0.5 sec

(c)  0.25 sec                           

(d)  2.0 sec

Ans (b)

10.

The time period of oscillation of a bar magnet suspended horizontally along the magnetic meridian is T₀. If this magnet is replaced by another magnet of the same size and pole strength but with double the mass, the new time period will be

(a)  \frac{{{{T}_{0}}}}{2}                      

(b)  \frac{{{{T}_{0}}}}{{\sqrt{2}}}

(c)  \sqrt{2}{{T}_{0}}                             

(d)  2{{T}_{0}}

Ans (c)

11.

Which of the following statement is not the true

(a)  While taking reading of tangent galvanometer, the plane of the coil must be set at right angles to the earth’s magnetic meridian

(b)   A short magnet is used in a tangent galvanometer since a long magnet would be heavy and may not easily move

(c)  Measurements with the tangent galvanometer will be more accurate when the deflection is around 45^o

(d)  A tangent galvanometer can not be used in the polar region

Ans (a)

12.

A magnet oscillating in a horizontal plane has a time period of 2 second at a place where the angle of dip is 30^o and 3 seconds at another place where the angle of dip is 60^o. The ratio of resultant magnetic fields at the two places is

(a)       \frac{{4\sqrt{3}}}{7}                                          

(b)       \frac{4}{{9\sqrt{3}}}

(c)       \frac{9}{{4\sqrt{3}}}                                          

(d)       \frac{9}{{\sqrt{3}}}

Ans (c)